FortressCraft Evolved [official site] is a Minecraftbut with large-scale industrial automisation, alien invaders, turret defenses and... wait, as Minecraftbuts go, that's a pretty impressive lineup of 'withs'. When I first saw FortressCraft on Xbox Live Indie Games years ago, it was Minecraft but with shiny water, but now... I'm quite surprised. After two years on Steam Early Access, FortressCraft Evolved [officially its name has an exclamation mark, but no -ed.] is... not finished, but it has left Early Access. It's complicated.
Let's blast the details out the way then get onto the tricky stuff. FortressCraft Evolved is a sci-fi craft-o-explore-a-builder starting from dirt and building up to, well, a colossal orbital power transmitter. You can start building machinery to automate tasks, and slap down turrets to defend your stuff, and it all spirals far beyond the scope of Minecraft. It's out on Windows, Mac, and Linux for £7.99 right now. Player reviews on Steam are looking pretty positive.
As for leaving Early Access... creator Adam Sawkins explains that no, it's not finished, and indeed nor is any game ever. Bit weasley, that. It seems he wanted to escape gripes that the game wasn't finished and the Early Access stigma, so he's declared it done enough after two months of work on polish and improving the new player experience. He says it'll take about 300 hours of play to reach what he considers the current end, but he'd like to keep working on it - if he can afford to.
Minecraft wasn't done when it launched, of course, and still isn't, but Mojang were sitting on enough money to put contracts on the heads of every last person reading this. Sawkins is not. He explains that while he's got ideas for another few years of additions, and would dearly like to keep working on it for yonks, the game has averaged about half the sales he needs to keep going.
As ever, if you don't have money to spare, make purchase decisions based on the state of a game as it is now, rather than dreams of its future. FortressCraft's present state does look interesting as cube 'em ups go, mind.