I played the first game on PC, and I liked it. Not the very best retro shooter, but good enough to have a good time. I don't know how well it runs on the Steam Deck, but considering how light it was, it will probably run very well.
Project Warlock II is in early access. So I'm waiting for the final release.
The soundtrack is made by Andrew Hulshult and it's freacking amazing.
I played it on hard, but I regret doing it. I should have gone a level up, to get more of a challenge.
Might play it again on very hard.
Here is the playlist for the soundtrack, on the youtube channel of Andrew Hulshult.