I've always admired how Space Engineers stuck to its guns - while it may have added a couple small scripted scenarios, it's still just a game about building, with no overarching plot. Even as it exits early access today and launches in full, Keen Software's game about being an astronaut engineer remains a true sandbox. Players bodge together improvised spacecraft (optionally with friends) and make their own fun. Whether that fun involves solitary mining and construction or multiplayer team shooter scenarios is up to the players. See the launch trailer below.
Today's launch version of the game is accompanied by a massive change-log, including an overhaul of Survival mode plus a boatload of smaller changes, including a lot of new blocks. There is a new combat scenario called Never Surrender, which tasks players with defending a small asteroid outpost against automated drones, but even that is open-ended. There's a new scenario introducing players to the revised survival mode, where players need to worry about mining and processing resources, rather than just popping a spacecraft into existence before your eyes.
The new survival mode features a progression tree to slowly dole out new kinds of space-tech, and there's some mention of new encounters as well. A while back, the game added giant spiders which were a nasty surprise for players bumbling around in the most gently paced sandbox modes, and there are some 'pirate' enemies scattered around to fight. It's not a completely barren universe, but one where you don't have to fight if you don't feel like it.
Oh, and last but not least, they've added ladders back into the game - an early feature, removed due to being buggy, you can once more ascend to lofty heights without the use of ramps or jetpacks.