Cataclysm: Dark Days Ahead is a very fun open source roguelike game currently under active development, unlike a traditional fantasty roguelike this is set in a post apocalyptic world that has been overrun with undead zombies and various other monsters, the only goal is for you to survive, which, like most roguelikes is quite a challenge.
As is typical there is quite heavy use of proceedural generation to produce the game world, this consists mainly of random cities connected by roads, in each city there are various buildings such as houses, hardware shops, grocery stores, etc, which can all be looted provided you can get past the monsters that is.
In addition to the standard buildings there are a variety of larger buildings such as shopping malls, hospitals and apartment buildings along with much more dangerous but highly rewarding locations.
Despite the world being essentially unlimited it doesn’t really feel empty, there is always a zombie or human (friendly or not) to to keep you company, you will also come across various situations such as a drugs deal gone bad for some easy loot, as well as situations that could get you brutally killed.
Once a world has been generated you make a character by choosing their starting scenario, profession, traits, attributes and skills, each of these costs points which you can gain by picking something negative, such as a harder starting scenario.
Like a real person your character needs to eat, drink and sleep, for new players this can be a fairly daunting task but you’ll eventually get the hang of it, you will likely die quite often and like most roguelikes this deletes your save, however your character will remain in the world so you can potentially recover your equipment, assuming your dead corpse has not walked off yet.
Performing various actions increases your skills which make you more effective in combat as well as unlocking new crafting options which are vital for your survival, you can also read books you find to rapidly increase your skills.
One particularly interesting aspect is that each item has a volume as well as a weight, so for example empty plastic bottles may have little weight but they take up significant volume, good choice of clothing and other accessories can increase how much you can carry at the expensive of greater encumberment, clothing is also vital to keep you warm particularly in winter, this may sound inconvenient but there are plenty of ways to move a large number of items.
The crafting and construction system is one of the highlights of Cataclysm, there is a huge number of useful, and not so useful items you can produce from high quality food to improvised firearms, the construction system also allows you to build you own shelter among other things.
Vehicles play an important role, since the world is quite large and resources limited you may find you eventually need to move, vehicles are essentially mobile bases and you can outfit them as you wish (provided you have the skill and parts), in a way this gives the game a very Mad Max vibe as you mow down zombies with your giant death fortress.
Cataclysm is a very difficult game to master but also very rewarding, new content is constantly being added and there are a variety of mods that add even more stuff, don’t let the simple graphics and controls put you off giving this game a go.
I suggest downloading the experimental build as the stable one is extremely out of date.