Robocraft is an early access mash-up of World of Tanks and voxel building, letting players build land and air vehicles and then take them into online arenas to do battle. Chris thought the "tinkering is actually more fun than the tankering," when he played it back in July, though both are likely better after the latest update added wall-scaling, crawling vehicles to its already hefty number of customisation options.
Of all the long-running multiplayer Early Access games, I find Robocraft the most tempting. One of my flatmates was well into it a month or so ago and I spent more hours than I'm willing to admit cheerleading him and his increasingly large and violent mechanical babies. It's one of the few grand, alpha ideas that seems to be achieving its goals; it's just the right combo of fast-paced and easy-to-learn with a creative side to draw in a crowd. A quick glance at the game's dedicated subreddit revealed both great originality and skilled references. And, well, this.
The update's also added the ability to engage in "boss battles" where a higher tier player - with naturally stronger guns and armour - faces off against 20 lower tier ones. These are scattered into the match-making, so they occur randomly when searching for normal games. It's a brilliant idea, giving newer players some idea of what they'll get to do later on while also allowing for a big XP bonus if they manage to survive and triumph.