http://planetexplorers.pathea.net/

This game is in alpha, its free to download and play.

Has all the sandbox elements and most of them are working in the alpha stages. This game is further along in alpha than most release games in the indi sandbox genre.
If you like Sci Fi, and sandbox, you don't want to miss out on getting in early on this one.

Here is a video link for you as well.....

http://www.youtube.com/watch?v=qCJbWRtr8lM

Got funded through Kick Starter

Currently on Steam working towards Green Light
http://steamcommunity.com/sharedfile.../?id=129199308

Currently has a post Kick Starter campaign going through Paypal
http://planetexplorers.pathea.net/preorder/