Nice little underwater twist that Minecraft players are going to enjoy. The terrain in the game is smoother, so it's not exactly a voxel game, but rogue-like to be sure. The only issue is that the developer felt it was necessary to cut development on the game early (I'll give the developer credit for being honest, but a lot of people are not happy about this), so the capabilities of what you can craft in the game is easily lacking when you look at the number of other voxel games on the market. Because of the lack of content & how short the game is, I wouldn't suggest purchasing at full price, but definitely when on a sale.
A few issues I'm going to note here:
The game does not have any means of time tracking as far as I can see, so you can easily get caught out after dark & get pummeled by attacking fish/sharks where you can't move fast enough to dodge or run from them. If you have a weapon, you can at least defend yourself to a point, but you're still going to get hit considering it takes several spears to take most predators down.
There are some areas in the game that you might get stuck on the terrain (happened to me a few times in my base); a simple hop should get you moving again.
The game does not remember your resolution settings, so you will need to reset this every time you restart the game.
There is no tutorial in the game, so you may end up have to use trial & error & the Steam forums to figure out what you need to do to actually play the game.
The crafting requirements are displayed for things you are attempting to craft, but all you get is a small icon with no indication as to what you're looking at. The crafting menu is simplified similar to Terraria & Starbound, but the lack of ability to find out what each icon is (not to mention some of them look very similar with only a slight color difference; take copper & gold for example), can cause confusion & isn't really helpful.
Occasionally you'll run into sunken ships, these don't seem to have any effect in the game regardless of being shown on your map. I would assume an unfinished feature; the only thing I can see that has any relevance to them is you will occasionally find up to 4 item chests strung around them, but with the item chests having their own map makers, there's really no reason in including a ship icon as well with no purpose other than higher probability of these chests.
Only a number of resources actually have map icons. This is understandable when you consider Iron is literally everywhere, but the rarer resources are harder to find & for the most part don't have a map icon. Dirt, Coal & Gold all have map icons, but for the most part unlimited resources do not (although Dirt & Coal apparently fit under this category). The first resource you're going to have trouble locating is Copper & considering their is no map icon for it, you may have trouble locating it again when you need Copper as there is no way I can see to set a marker on you map. There is however another means to do this & that is to drop an Extractor right on top of it. This not only continues to mine the material while you're away from it, but the Extractor itself has a map icon, making it easier to re-locate it. My suggestion on this is to always have at least one Extractor on hand so you can mark rare resource locations to come back to later.
While chests with items do have map markers, chests with coins do not. Coins are used in Sandbox mode to start you off with equipment. While you are not required to start with equipment in sandbox mode, it does make it a lot easier to deal with.
Droids could have been better designed. Once you have activated one, they follow you around as a means of extra storage space for items you pick up. The problem here is that in order to call a drone to you, you have to first locate them, then press the Activation button while targeting them. I think a better method for this would have been to use a controller or keybinding, but unfortunately there is no easy method to call them to you. The plus side to using drones is that any items on the drone do not get dropped if you die; only the items on your own body get dropped when you die. Drones are a good way to safeguard items you may have found before getting back to your base without having to fear not getting back to your body after a death to retrieve those items; this works EXTREMELY well when it's getting dark & you know you're not going to get back to the base before you start getting attacked.
This game still easily makes it on my favorite list; it doesn't really matter if it's a short game or not, rogue-likes give games a high replay value & keeps things interesting. As far as functionality & user-friendly is concerned, the game is lacking & not extremely easy to learn for those who haven't played voxel games before & as far as crafting is concerned, it probably has the lowest inventory capabilities of any voxel game out there. Plus some features seem unfinished, so I can't exactly say the game is worth the $15 price tag, but if you can get the game for approximately a third of the price, you're looking at a pretty decent game.