I was going to write a good review, then I reached the end abruptly.
in my 8.2 hours of playing I finished the game, but a good 3-4 hours of it was catching up a friend in multiplayer, so the game can be wrapped in about five or six hours if you have played a survival game like terraria and such before, and a few more if you arent really good at platformer/shooters, I found a couple "Exploits" that helped me along a bit.
Unfortunately, the content is extremely limited, and consists of a set of portals (Which, by the way are not as random as the game would lead you to believe) every tier portal was the same in multi and single, so there is about 9 'dungeon portals' to clear out. and the same number of tiers of ore, unfortunately these tiers kind of overlap and you can easily skip a few if you craft and are good at platformers, once you reach the bottom and clear the last portal: Thats it: it gives you "God mode" and "Creative mode" and infinite everything. some of the dungeons didn't even have bosses, just "hard" Rooms (high damage enemies) at the end of them. Other reviewers have experienced the same thing, its nothing but a numbers battle, very unimaginative design, anything it didnt steal directly from terraria (Except the projectile-based mining! That is the ONLY redeeming mechanic I found, personally... but the rest of it..) was not very good. Clunky inventory/hotbar, movement feels very rigid, and aside from increased jump and reduced fall damage, theres nothing cool like a jetpack or wings or doublejump to help you move around.
For ten bucks there is quite a few more action platformer survival games that will keep you playing for longer, and have a better progression model, as well as much more varied content, as this is reall just "Mine to next portal, clear, craft, mine to next portal...."
There are some pretty obvious and game breaking bugs too... i hesitate to mention them here so...
I could have probably had a bit more difficulty with the game, but, I love my hardware and I macro'd a fire button and since the blaster has 0 cooldown it fires rather fast, gg until tier 4, then I found out if I hold an item and shoot it would (About 80% of the time) fire charged up shots rather than standard ones, and still work with my macro, so I had a rapid-fire charged blaster to get me through some of the tougher battles (Which as I said, were just high damage enemies, nothing "Hard")
TLDR: Great concept as games like Terraria have proven, but heavily lacking in content and very short. Also some very game breaking exploits/bugs. For ten bucks you might as well spring for Terraria, or Edge of Space, or countless other games in this genre. This one is NOT in early access so this is a finished product. Money could have been spent elsewhere.