Red Orchestra. The standalone game was good, but bonus points if you use the UT2k4 mod first. The bots are serviceable to at least experience the game a bit.
Deadly Dozen Pacific Theater had some interesting gameplay to it. It’s a blast sniping everything in that one
I got a HON Ignition 2.0 a few years back for about $300. Don’t let the name fool you, it’s not a gaming chair. It’s one of the best cheap ergonomic chairs I’ve ever used. You can get them lightly used from Amazon for about $360 nowadays, or $425 new. Between working from home and sitting in front of my computer gaming, I spend probably 8+ hours a day sitting in that chair, and have for the last 3 years. It’s still in great shape and shows almost no wear and tear.