Category Archives: Game Development

Game Dev Update: Twisty little passages, all alike

A quick update this time — I’ve been working here and there on implementing some maze generation code for the game, so that I could have a few different types of dungeon levels to generate.  At last I’ve got it working, and can now generate some intimidating mazes using the ‘growing tree’ algorithm:


By altering the likelihood of new branches in the path, I can change the feel of the maze significantly.  The maze above has a high likelihood of producing new branches; the one below produces much longer hallways:



Tonight I’ve just added a variation of this algorithm which mimics another well-known maze generation method, the ‘recursive backtracker’.  This one needs some fine-tuning, though, as currently it produces very long, meandering corridors that can be a little annoying to navigate:


The next step is to make the maze generator a bit more flexible.  Ultimately what I’d like to do is allow the normal dungeon generator to create maze rooms which can be integrated into the rest of the dungeon.  This will add some more variety in the dungeon without forcing the player to navigate an entire level-spanning maze every time the dungeon generator decides to mix things up.

I do think I want to have one dungeon level that’s entirely a maze, though, and encourage exploration by sticking a powerful artifact somewhere within and dropping some hints that the player might find it if they have a look around.  I’ll also scatter some Scrolls of Clairvoyance about, which will reveal the location of the level exit and make navigating the maze less directionless.

As you might’ve guessed, in these screenshots I’ve switched off the ‘fog of war’ for the player so that I could observe and test the results of the maze generator.  In actual play things look more like this:


By way of comparison, here’s how a maze level looks in the famous(ly difficult) roguelike Nethack:

Image result for nethack gehennom

More to come next time, when hopefully I’ll have maze rooms working.


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Game Dev Update: Upping the Challenge

So it’s been a little bit since the last update on my hobbyist game development efforts, but a lot’s been going on whenever I can snatch some time in between the constant, endless presentations I’ve had to prepare for recently on the academic side of my life.

My focus in the last few weeks has been on some core gameplay systems.  Originally I was going to work on the dungeon environment, but I figured that fancy dungeons wouldn’t be that useful if the player couldn’t do interesting stuff in them, so I went for under-the-hood gameplay systems instead:

Hunger system

Hunger systems are a classic feature of roguelikes — since the original Rogue, in fact!  The idea is that the player needs to seek out food within the dungeon and eat it regularly, otherwise they gradually begin to starve to death.  Since food is limited and can only be found within the dungeon and not created by the player, it serves as a time pressure mechanism; the player has to keep moving further down the dungeon to find food in order to stay alive.  Currently my system is very basic: the player starts with three rations, and can find two different types of food items within the dungeon that refills their hunger meter.  If at any point your Satiety stat dips below 50, you start getting warnings, and at 0 begin taking damage every turn.  At -50 you’ll die of starvation.  I’ve added an indicator to the interface that shows this stat directly, unlike Rogue and some other games that keep it hidden and only warn you shortly before death:


Turn Scheduling:

In order to make monster fighting more interesting, I wanted to add a system for variable attack and movement speeds between different creatures.  This is kind of a weird thing to implement in a turn-based game, and I wasn’t sure of the best way to go about it at first.  Eventually I settled on a central turn scheduling system in which all monsters (and the player) schedule their next turn each time they take an action.  The number of turns they have to wait until they can move or attack again depends on their Speed stat.

It sounds simple, but it turned out to be a big pain to get right!  I had a lot of weird bugs where certain monster turns didn’t register, or the game would suddenly stop running in turn-based mode and let monsters run rampant while the player was unable to move, and all sorts of other problems.  Eventually I got all that ironed out, and finally had fast-moving wolves and bats, slow-moving zombies, etc… only to find that in certain circumstances the player would encounter invisible and invincible enemies after moving to a new dungeon level.

After a few days of annoyance I worked out the problem — monsters were dying in combat, but a reference to them was remaining in the turn schedule, meaning that memory was still being allocated for their monster data by the program.  In certain situations that meant the scheduler would find that reference, say to itself ‘hey this here says there should be an orc doing something’ and the player would end up fighting a ghostly remnant of a previously defeated enemy!

I was able to fix that relatively easily once I figured it out — this is why we keep backups, kids.  Also it was a useful reminder to be more careful about my coding practices in some parts of the game, so I did quite a few bits of refactoring of the code to prevent anything like that happening again.

Combat System Changes:

Again in service of making combat more interesting I made some significant changes to the combat system to better differentiate enemies.  My favourite series of Japanese RPG games is the Shin Megami Tensei series, which are known for being set in a dark demon-infested version of Tokyo and for being really difficult.  What I love most about these games is that the combat system encourages tactical thinking by having weapons and spells deal a number of different types of damage, which demons can be weak to, immune to, or resistant to depending on their nature.

I implemented something similar to this, where each monster has weaknesses to certain types of physical damage (in this game they’re called Phys for general slashing attacks, Blunt for hammers/clubs, Pierce for arrows and spears, alongside numerous magical damage types like Fire, Ice, Thunder, etc.).  Hitting a monster’s weakness will do double damage to it, while hitting if it’s resistant you’ll deal only half damage.  Some monsters are immune to certain types of damage entirely — Skeleton Warriors, for example, aren’t bothered at all about being poked by arrows given their total lack of fleshy bits.

The idea is that this will push the player to experiment with different weapons, spells and items in order to dispatch enemies more quickly — particularly when they reach later dungeon levels, where monsters start appearing in large swarms and have powerful attacks.  I want damage types to be a major focus for the player, and for good attack choices to have significant rewards (and for bad choices to have a big impact!).

To make things a little easier for the player, I’ve added a Look command so that you can see some details about monsters in visual range:


Other than these big changes, mostly I’ve been squashing bugs and adding bits and pieces of content.  At this point, the player can face about 300 different monsters, collect 50 different weapons and items, and visit 15 different dungeon levels.  As time goes on I’ll keep adding new monster types, then randomly-generated weapons and items, and finally some super-tough boss monsters including a final boss.  At that point I think I’ll be ready for a playable alpha release to get some gameplay feedback.

This week has marked the official start of the academic year, so there’s been a ton of things to do at the university — which means there hasn’t been much time for game development!  I’ve been keeping careful track of all my additions and to-do lists and such, so when I have time to get back to things I’ll remember what I’d planned to do next.

All in all it’s a hell of a lot of fun so far, even when I’m getting frustrated by weird bugs.  I’m definitely gaining some major Python proficiency thanks to all this, and it’s forced me to tighten up my coding practices and embrace proper version control.

After some more work on damage types and attack variety I’ll be modifying the game UI and sprucing up the general look of things, so hopefully I’ll have some more interesting screenshots next time 🙂

I’ll leave you now with some game recommendations:

SDL Rogue: a well-done Windows port of the original Rogue, with some nice additional options (including a graphical tile option).  Type ‘?’ to see all the commands (there’s a lot of them!).  The same site also has similar ports of other classic roguelikes, including Hack (the predecessor to Nethack), Larn, and Moria (predecessor to Angband).  Check ’em out.

DoomRL:  This is a fantastic free game that combines two of my favourite things — the original Doom (in my opinion the greatest computer game of all time, and one I still play regularly), and roguelikes.  It masterfully combines frantic Doom-style demon-blasting with turn-based roguelike gameplay and character progression, and to top it off has the original Doom music and sound effects, and some fantastic 2D graphical tiles.  Download it!

Some enterprising fan has developed a server for DoomRL, too, so you can see how you stack up against other players and even play in your browser (or via a Telnet client).  ASCII text mode only though!

Crypt of the NecroDancer:  This game kicks my butt all over town, but it’s incredibly creative and fun.  It’s a turn-based roguelike with a twist: the entire game world is tied to the rhythm of the music for the level, and making your moves along with the beat gives you various bonuses (and moving out of time leaves you open to attack!).  All the items and monsters play on this theme.  The graphics are incredibly charming, the music is by Danny Baranowsky (of Binding of Isaac and Super Meat Boy fame) and is absolutely fantastic, and it’s packed to the brim with cool features and secrets to unlock.

It’s also 50% off on Steam right now, so now’s a great time to take the plunge!

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Diversions: Game Dev Update


So in my evening hours I’ve been working away on the roguelike game development project.  For the most part I’ve been really pleased with how well it’s trucking along — I’ve seen a number of other roguelike projects out there using Libtcod that fizzled out way before adding this amount of content, so I feel confident I can finish this project.

Having said that, it’s requiring a ton of changes in my coding practices.  Even in just a couple of weeks of development time, my game has expanded to the point where every addition has a large number of potential interactions with all the other game components, so I’ve had to give in and embrace version control.  Every change is archived on my own machine, then on Google Drive, and finally uploaded, checked, and merged into the master code branch on GitHub.  I’ve never bothered to do this before, but with this project (where just adding a new potion can cause weird stuff like making monsters stop moving completely until I find some minor malfunction) I’ve found I need to make it as simple as possible to back up a step when something goes strange.

I’ve added a few major gameplay additions since my last post.  One of them appears right at the start of the game — you can now choose a character role when you start the game.  Fighters are focused on close-range combat, Knights carry a shield which gives them great survivability, Archers are great at long-distance but weak up close, and finally Wizards are incredibly fragile but start with powerful spells.  Here’s a wizard who’s just managed to turn a wolf to stone:


You might notice that I’ve been experimenting with the ASCII visual presentation too — the plan is to have some colour schemes for each set of dungeon levels, and each set will have particular characteristics and terrain hazards too.  I’ve also changed the lighting slightly, heightening the contrast between explored and unexplored squares, and I’ve changed the font to a 16×16 version of Terminal that I think is a bit easier on the eyes.

Since I’ve introduced Wizards, I’ve also introduced the beginnings of a magic system — although there’s a lot left to do in this area.  I’ve followed the lead of other roguelikes and developed a system of wand items — these drop randomly in the dungeon or from certain enemies, and give you a limited number of uses of a specific spell.  I’ve added eight wands, each with two varieties, as a first test of the magic system and how it affects play.  Later I’ll be adding a system for Wizards to learn spells permanently, a resource system to restrict usage, and more detailed stats for players and monsters to make certain spells more effective against particular opponents.

I particularly enjoyed making the Petrification effect — it turns the monster into stone, of course, which then blocks visibility and movement.  So you can use it tactically to block off other monsters and restrict their movement or vision.  When you tire of it you can destroy the statue and it crumbles into rocks (which you’ll be able to use as ammo for a sling, once I make that).

As for monsters, I’ve added a few of those, but more importantly I’ve added a random mutation system for monster creation.  When a monster is generated, there’s a small chance that the monster will be mutated either one or two times, and each mutation will add statistical bonuses and special abilities, as well as alter the monster’s name and display colour.  I’ve only added six mutators so far, but that’s already enough to significantly increase the game variety.  Honestly I probably spend more time play-testing than I really should when I have coding time — but I think that’s a good sign if I’m already finding it fun to play!  The mutators will be even better once I add more monster types — these are taking time as each monster type has it’s own AI function which takes a lot of testing to get right.

Here’s a Fighter who’s run into a Hellfire Troll, a significantly stronger mutation of the already difficult Troll:


All told it’s been a productive week.  My goal for the weekend is to jazz up the dungeon environment significantly, first by setting up the visual themes and names for each level subset, then developing a system for adding terrain features, some of which will be interactive (think stuff like lakes, lava flows, grass, fungus, rock pillars, etc.).

After that there’s some major tasks in my development plan:

  • Flesh out the magic system (which will need a bunch of interrelated items and systems to go with it)
  • AI and game systems for allied characters (in some circumstances players will be able to raise some troops, by resurrecting dead monsters or brainwashing living ones)
  • Methods for random generation of items

Again none of these are new ideas — my design goal here is simply to make a complete roguelike in the classic style, with just a bit more playability and transparency.  Once it’s done I’ve got some ideas for game #2 — but I’m not allowing myself to think much about that now!

Speaking of roguelikes in the classic style, thanks to some dedicated roguelike fans out there you can actually still play the original Rogue on modern computers.  It’s still quite playable, albeit mercilessly hard — winning Rogue is a real accomplishment.

You can also still play Moria — the seminal early roguelike based on Tolkien which later spawned Angband.  Really though I’d recommend trying Angband if you want to try a classic roguelike — it’s much more user-friendly, has lots more content, and has a graphical mode.

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A Diversion: A First Attempt at Game Development


As my friends and colleagues are aware, my favourite hobby outside the academic sphere is gaming.  In particular I have a fondness for very difficult games that require some tactical thinking to survive — so I’m a big fan of roguelikes.

For those of you who don’t know what a roguelike is, I’ll share with you a too-lengthy post I made on Facebook by way of explanation:

My game is a ‘roguelike’, a genre named for a very popular game in this style from 1980 called Rogue. There’s some debate about how to define roguelikes precisely, but generally they’re characterised by:

1) Turn-based gameplay — you take a turn, then the enemies. You can take as long as you like to think about each action and its consequences.

2) Randomly-generated levels — often you dive into a very long, multi-level dungeon full of monsters, items and fiendish traps, and every level is randomly generated each time you play, meaning you never run out of levels to play and no play-through is ever the same. In my game dungeons are generated using BSP trees which is a pretty common method.

3) Permanent death — if your character dies, that’s it, you have to start over from the beginning! What’s more, most games (including mine) automatically save the entire game state after every move, and overwrite your saved game when you reload a save, meaning that you can’t ever go back to a previous turn. Every action has permanent consequences.

4) Text-based graphics are usually a feature of every roguelike in the classic style, even today in 2016. Graphical modes are normally an option nowadays too, but many people prefer text mode (including me) because once you get used to it the text actually makes it much easier to determine exactly what’s in front of you at any given time, which is important because…

5) …while the graphics are often simple, the gameplay is normally quite complicated. Hundreds of items, monsters, and environmental features are in these games, all of which can interact in tons of different ways — not needing to make fancy animations for everything means developers can go nuts with the gameplay systems.

Anyway those are the main features you see in the genre — most of the major games in the genre are completely free, so I recommend trying them. The site RogueBasin has links to the five ‘major roguelikes’ right on the front page — ADOM, Angband, Crawl, NetHack and ToME. In my opinion Crawl or ToME are probably the easiest places to start, given they have pretty nice visuals and decent tutorials for new players. Angband is a long-time classic and has a decent graphical mode included as well. NetHack is famous for having insanely detailed game systems and item interactions, but is a bit overwhelming for newcomers.

My game is very early in development, although the core gameplay systems are all functional (random dungeons, character progression, combat, item and magic systems) and it’s fully playable. Not bad IMO given I only started making it five days ago, but there’s a long way to go yet. My goal is to add at least one new gameplay feature, monster, item, etc. every day for the next couple months so I can gradually build up a complex but balanced gameplay experience.

Given that this is my first-ever foray into making a complete game — I don’t count my failed attempts to write code for the GameBoy Advance back in 2005 — I’m pretty pleased with my progress, and it’s certainly been an enjoyable and challenging way to spend a few days of my summer holiday.

I started off by following the Complete Roguelike Tutorial using Python 2.7 with Libtcod — this gets you a complete, playable prototype (albeit very simple).  Since then I’ve added quite a few major features, each of which has required learning a bunch of new algorithms or techniques:

  • A* pathfinding for monsters
  • Random dungeon generation via BSP trees
  • A graphical version (using free 16×16 tiles made for Angband)
  • A more complex combat system including dicerolls and critical hits
  • Damage-over-time (poison attacks)
  • A complete ranged combat system including ammo tracking and relevant attributes for the player and enemies
  • Several new AI routines designed for specific enemies, i.e.:
    • Wolves that call for their pack mates when in trouble
    • Snakes that stay at a distance and spit poison
    • Enemy archers who try to get the drop on you

Now that the core gameplay systems are mostly there, and the return to academic life is looming, I’ll be slowing down significantly from here.  My goal is to build on this foundation bit by bit over the coming weeks and months, until I have a cohesive 20-floor dungeon-crawl experience with quite a few dozen monsters, items and weapons to discover.  This is a bit of an experiment for me, and I may not release this game to the larger world and instead bank this experience for a better follow-up project.  Having said that, once it’s in a more complete state I’d welcome any interested play-testers!

I should note that if I do end up releasing this it’ll be completely free, and probably open-source, assuming my code isn’t too embarrassing.

Since this is ostensibly an academic blog I should say that part of what pushed me to finally take the plunge and try to make something like this was actually some of the students I advised last academic year.  A large proportion of my advisees were game development students, and I wished I’d had more domain-specific knowledge to help them through certain problems.  Now at least I can tell them where to look when I hear from students who are stuck on pathfinding, AI issues, etc.!

Before I leave you, a screenshot of the fabulous ASCII graphics I’ve been staring at for hours on end:


And for the ASCII-shy, a screenshot of the graphical version:


More to come later — the graphical version is very much a side-project at the moment, so expect that to be spruced up as time goes on.  I’m planning to switch to the stylishly lo-fi tiles of Oryx Design Lab — they’re simple, visually clear, and as they’re uncoloured I can tint them a million ways to represent the requisite dozens of variations of every imaginable monster that roguelikes generally have.

If you think I’m exaggerating — NetHack variant Slash ‘Em Extended boasts 12,221 monster species.  I think I’ll stop long before the 12,000 mark though.

That’s enough out of me for today — I’ll post updates on here every so often, if I find any particularly interesting techniques or come up with a version polished enough to distribute.



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