To pre-empt questions about ARMA 3: It doesn't advertise it, but it has an "experimental" Linux version on Steam ported by Virtual Programming and it's not bad. Just download, install, play.
Both games are on sale as well, so if you decide you like either of them, you can pick them up cheap!
A little tip about Day of Infamy too, it has issues where it won't show you as in-game once it's loaded, which breaks the party and Steam invite system. To get around it, for now you can open your install folder and set the "crash_handler" as not executable. I've reached out to the developer again to let them know of the issue.
Also, to celebrate "Alien Day" you can find Alien Isolation on Humble Store with 75% off until Monday. Steam also has it, but their sale ends sooner.
Humble also still have the current Humble Monthly with 7 days left, which will grant you instant access to RUINER, Kerbal Space Program and Moon Hunters. Additionally, you get access to a ton of DRM free games in the Humble Trove. Probably one of the best monthly bundles for Linux gamers in a while and you can cancel any time.
For those interested in more hot FPS action, our old favourite Ballistic Overkill is also on sale with 50% off on Humble Store.
It's likely I will be jumping into Day of Infamy tonight on the GamingOnLinux Friday livestream, so be sure to follow us on Twitch or download it for the free weekend to join in on the fun!