Well I'm just asking because there are a lot of obscure titles here, which is why I keep coming back to this thread as a reference to find new ones I'd likely never find on my own. I tend to get lost sometimes though, not that you don't have it organized well but because there's just so many, and I don't really know how popular they all are. I don't really have the time to just try them all myself.
You put a lot of work into this, and I really can't ask for more, but a lot of the game details aren't very personal, they're just developer descriptions so I don't actually know your thoughts on them. Personally I'm mostly a fan of RPGs, strategy, and shooters. Co-op multiplayer is nice, but only if there is a very active community with dedicated servers to play on, otherwise just single player.
Yeah. It's intentional that I don't 'review' the games too much outside of a small comment here or there. I think reviews should be empirical - Story/Description, System Requirements, Warnings about mature content, Warnings about bugs/errors/glitches and genre.
For strategy games I would try 'Glest' - It has a large mod community and 'Dwarf Fortress' - You can spend years finding all of the mods for that one and still not hit a 1/10 of what's out there.
For shooters (I think you mean FPS?) - I would get on 'HL2: Deathmatch' - Lots of mods, maps and dedicated servers. There are a few CO-OP maps where you and others take on custom made bosses and such in a mode that looks and feels a lot like UT 2k4 Invasion mode. For CO-OP FPS I would go with AA3, Tremulous and AVA not many mods there but lots of players and servers.
For RPGs games I would try games like 'Dungeon Crawl Stone Soup', 'Iter Vehemens ad Necem', 'Linley's Dungeon Crawl aka Crawl', 'Nazghul' and 'Nethack' - They are not pretty but lots of campaigns and mods available with some very devoted crowds.