Starmade

Starmade is a fantastically fun little game made by Schema. It's free to play (for now) and is in Alpha. By Alpha, I mean VERY alpha. It's basically Minecraft in space and has seen a lot of reasonable high-profile coverage recently including by the Yogscast. For the 3 people that have played Minecraft and don't know - they're pretty much the biggest partner on YouTube for Minecraft-related stuff, and even indie-gaming in general.

Starmade has MASSIVE scope for game that's only in alpha and if you played Creative Mode in Minecraft and enjoyed it, then Starmade is a great alternative for tackling creative urges.

I've touched on the creative possibilities that others have already explored on my EVE blog, but here's some more screenshots of what I and some of the guys I play with have been working on (click on each image for larger version):

 Rex_Starfucker decided to blow a hole in the shop. Logic dictated I needed to make a station to fill this gap. Currently powered by 2xAA batteries (houses shields and power), a factory for when crafting is fixed, and a dry-docks for two of my cruisers. The ship in the top-left is the Bhaalgorn which is WIP and can be seen below.

This is why you don't do PvP around the home station.... Stretch's glorious Vengeful_Spirit copped a wayward missile. Unfortunately I don't have a "before" shot, and he didn't save the ship in the catalogue!. FUUUUUUUUUUU.

You can save ships into a catalogue and buy them in at any time using in-game currency. Fantastic for PvP (test a ship and blow the crap out of it) but you have to actually save the ship first :(

 This is a WIP for Bobb. Pretty clear what he's working on* but shows the scale you can get to - it's MUCH easier to go bigger than Minecraft, and the game has symmetry planes and the ability to change your "brush size" which helps to no end with large ships.
* In case you really couldn't work it out - the Enterprise.

Lastly - a WIP of my Bhaalgorn - modelled after an Armageddon/Bhaalgorn from EVE Online.

I'll finish up with a copy/paste of my conclusion in the EVE blog:
Because of balance issues, getting to what currently passes for "end-game" content is faaaaar too easy. If you want to play it now, I'd recommend playing it as if it were Creative Mode Minecraft - use Dev commands for infinite resources. If you were more of a fan of Minecraft's Survival Mode or, say Terraria's PvE challenges, then maybe hold off until the game reaches Beta.

I'd definitely peg this as a game to keep an eye on.