I'm interested in getting one or the other. May be both. For those who've played them, which is the one to get? Why? Thanks.

Well, I never played sub level 0, but it looks super cool.

Though I'd say that if it were me I would go with it simply based on the fact that it's out and it's cheaper, Descent looks alright but it's still in early access, so I say get sublevel 0 now and then Descent when that comes out for real.

Apart from both being 6DOF shooters, they are fairly different.

Descent Underground is primarily focused on multiplayer, potentially with some single player missions coming down the line. Personally I haven't had any major issues with Descent: Underground, but I've heard enough people with technical problems with the game (GB haven't managed to even boot the game up the three or more times they've tried during streams). At the very least, I think you'd do best waiting for the final release of that.

Sublevel Zero is a singleplayer only run-based game/procedurally generated rogue-lite. You never play the same set of levels twice, and the loot and crafting system means you also may not come across the same weapon sets over the course of multiple runs either, but some people seem to really dislike the look and feel of levels that have been automatically assembled out of setpieces rather than handcrafted by a level designer, and of course with randomly generated weapons you're likely to come across stuff that's not particularly balanced or fit for the way you want to play. It's out and finished though, so it's easier to judge by what's there rather than what could potentially be there in the future, and for the most part, people seem to like it.

Unless you're looking for multiplayer, I'd probably lean towards Sublevel Zero.

Thanks for the input. Going with Sublevel Zero.