The Citadel

You die fast in this game, but your weapons are powerful, so it's all about assessing & approaching each situation correctly rather than automatically running in and nuking everything (though sometimes this is a valid tactic).

Shop progression & upgrades are solid; there's a couple of upgrades I didn't care for, but nothing that ever ruined the game.

It's fun, it's challenging (I played on the highest difficulty) and oozes style, the sequel just downloaded so I'm off to play that.

The sound design is fantastic as well; the music, sound effects, and to a degree voice clips as well all were high quality and massively contributed to the worldbuilding in ways the visuals could not; not to say the visuals didn't add to worldbuilding because they totally did with what they are in this style.

Sound design further enhances immersion, with weapon effects, enemy audio cues, and ambient noise contributing to a constant feeling of tension.