All my gaming progress has been on hold for 3 months due to new game : Dwarf Fortress.
its a complex, tough game where you have to build up a fully functional fortress from scratch and survive. Mostly survive, coz anything and everything can kill you.
Not enough food and booze? Dwarfs go angry and revolt. Not enough pants? revolt. A pet accidentally was butchered? REVOLT.
Also, it has dragons, invasions and many mosnteers.
WARNING : its cpu only, so gpu does not factor into the equation. also, its ASCII only, though graphical tilesets and sprites are available.
only play if you are looking for a challenge, its a game that will make you cry for your mistake, because you forgot to lock the door, allowing the kobold thieves to steal the king's favorite mail shirt, making him angry, so that he goes and pulls the lever that floods your fortress with magma.
also, all the dwarfs are total boozers, and actually suffer penalties when sober.
get it here (you have been warned) : Lazy Newb Pack [0.34.11] [V15] Updated GUI! ( just choose the advanced version, its got sweet utilities that can make your first fort easier)
screenshots : do you really want to look at ASCII graphics? just play the damn game, or better read the wiki.
wiki : DF2012:Quickstart guide - Dwarf Fortress Wiki (just look at that flowchart.... its freaking COMPLEX)
on reddit : Dwarf Fortress (very helpful community)
The wiki has everything you need to know, its your best friend. consult it at ALL TIMES.
you will need help many times, so dont be scared to ask for it.
go to the wiki, or join the irc chatroom, help is always available.