I didn’t see it suggested yet, but you should check out Selaco. It’s a fairly new FPS with tight gunplay and retro graphics. The enemies AI is well made, they will work together to hunt you and try to flank you. The weapons are a mix of standard fare with some new stuff, and you can modify them with upgrade packs similar to how Doom 2016 does it. The upgrades give each weapon a good variety for different play styles.

The first chapter is released and playable, and there are 2 more chapters coming. The first chapter has a good amount of gameplay, I put 35 hours in it.