The Endless Mission is described by developer and publisher E-Line Media as "a community-driven creation sandbox game where you play, mashup, and mod iconic game genres in order to make your own creations and experiences to share with the world." However, that was not the version of the game I demoed at PAX East this year.
Instead, I played a wave-style game mode where you defeat various enemies over the course of a set number of stages, and earn power-ups as you go. As always in The Endless Mission, everything in the environments is destructible, so you can hack through terrain as easily as you can enemies.
The combat focused on swords and abilities, so its vaguely fantasy-based, though the abilities are less like spells and more like coding that allows you to edit your enemies- either by taking them down in groups, moving them around, or hacking their AI to make them your allies.
The wave mode can be undertaken alone or with friends, and is a cute addition to the sandbox game that makes it a bit more traditional than the creation mode.
The Endless Mission is currently in Early Access on Steam, it will be launching out of Early Access later this year.