Half-Life Deathmatch: Source
I'm sure this game was a ton of fun back in the day but the community is completely dead. You'll most likely find a maximum of 20 or less playing this game and that's if you're lucky. There are also a bunch of mods for this game as well, so if you find it challenging to find a server, see if some of your buddies will play.
1. The gameplay is fun but very challenging at first, can take awhile to get use to.
2. Probably some of the best maps I’ve seen for a multiplayer title.
3. There are a crazy amount of mods.
1. Community is completely dead.
2. Graphics are very dated. (If you care about that..)
Overall, this game was a bunch of fun back in the day, great maps, tons of mods and a bunch of fun weapons that for the most part, are balanced pretty well. But the community is completely dead and I’d only recommend picking this game up for Garrys Mod, so you'll have extra content.