GTFO

Pros: Fun gameplay, fun stealth mechanics, unique world and story, fantastic co-op and a fairly short learning curve if you're familiar with FPS games, great enemy design and weaknesses, challenging, rewarding when accomplished, some dialogue options really humanize the squad in a fun way I haven't seen before; visually disconcerting with zerg-rush horror.

Gunplay and melee combat alike are both incredibly satisfying, and possess very high skill ceilings so there's always room to grow.

Also, this game is one of the most ATOMOSPHERIC games I have ever played, it has GREAT sound, immersive lighting and fog, and very distinct style and gun play.

GTFO combines both stealth and horde shooter mechanics alongside a nice dose of horror to create an incredibly compelling game, to say nothing of the overarching story.

The sound design is probably the best of any game I've played: guns sound punchy and powerful, crushing limbs and skulls with your melee feels visceral, and the noises enemies make can be genuinely terrifying (I myself was spooked a frankly embarrassing number of times by a certain scream in R3C1).

This retro-style DOS interface is the most powerful asset in your arsenal.