I tried Galaxy55, it's not bad but i'd like it better if i could download a client and change the controls (also the view is locked so it's impossible to look directly up or down).
The mining system is a bit weird and annoying, you have to collect different types of energy to collect different types of blocks, but the inventory is so small that it's a real hassle. You can't craft engines yet so your ship's size is limited unless you get lucky and find a rare abandoned ship to scavenge.
Also for now you're limited in the total number of planets (there's only a handful of systems, you can only modify 3 planets and if you want to free up a planet slot you can't go back to the planet removed from the slot). The hangar is fairly small too, so you can't make your ship too big.
I tried building a base but honestly unless you use raw materials, you'll have a hard time getting enough blocks to do something nice, not to mention it's utterly useless. Storage is a big problem, the best way so far is to place valuable blocks directly on a planet you're going to keep, near your ship beam. I tried making mining lanterns but they'd only work once placed, and you can't get them back, making them really wasteful (they need iron), compared to wooden lanterns. Same with the mining booster, way to waste iron for a tiny speed boost in a tiny area, and you can't pick them back either. I tried finding coral to make antigravity pads (wtf ? coral manipulates gravity?), to get the yellow energy fruits in the trees but no luck finding any coral.
I think it'll be a lot more fun to play when they add more recipes and a better form of storage.
Edit :
By the way, the lore is ridiculous : according to it, the humans found a portal in the antartic, leading to a new galaxy (Galaxy 55 - nevermind that galaxies are named differently). Since they are obviously able to build more-than-decent spaceships (FTL drives), why is it such a big deal ? There are over 200 billion stellar systems in our galaxy, why the need for a new galaxy ? I mean sure, having access to another galaxy is always nice, but it feels forced. Not only that but once you explore it, it contains only a couple systems... Why ? Why are people so ignorant of basic astronomy ?