Streets of Rogue, easily one of the top Early Access games going right now actually has an ending and it sounds quite amusing.
Writing in the lastest update, the developer said this about it (mild spoilers):
For those who don’t mind a bit of a spoiler, here’s how it works: You have to take down the Mayor, who can be found doing one of a number of activities in Mayor Village. As per the city’s remarkably ill-thought-out rules, whoever has the Mayor’s Hat and makes a speech at the podium gets to be the mayor.
They go on to mention that you don't actually have to kill them, instead you can face them at an election. There's different endings and achievements for whichever way you go about it.
While you can finish the game, the developer has made it clear they're far from finished with the game itself. They're planning a new character (it already has a lot), more changes to the Home Base mode (where you can unlock more stuff), adding more building layout variety, more mutators, optimisations and plenty more.