Disclaimer: I haven't purchased the game or its DLC on GOG. All of my experience with it is through Steam, so I can't speak to anything specific to the GOG release that may sway people to/from purchasing it here (aside from the lack of DRM, of course ;) This is easily one of the most entertaining games I've played in a long time, possibly ever. You can easily squeeze hundreds, if not thousands of hours out of it, and that's just with the base game. The expansions only add onto that - more characters, more items, more enemies and bosses, and plenty more ways for your run to suddenly do a 180, in either direction. The game plays like a mix of 2D Zelda, twin-sticks shooters, and rougelike/lites. You explore essentially a dungeon, floor by floor, fighting various enemies and bosses, collecting items and pickups along the way to help (or hinder) you as you progress. There are many other quirks to the game's mechanics - special room types, curses, how enemies attack/can be attacked, etc. - but that's the base of the experience. Each character also has their own quirks - Eve and Samson both play into a "take damage to do more damage" gimmick, Cain can make better use of gambling games and pills, Judas is basically a glass cannon, and the Lost is... well, painful (especially in the base game). My suggestion? Buy this game with its expansions - it's the most fleshed out, refined experience the game has to offer at this point.
