Played the demo, which is about an hour of content. The main conceit of the game is that endless waves of enemies advance toward you, and if they reach your lava moat they die without dropping loot or XP, so you have to kill them en route. There's an interesting balance between buffing your own units, in order to increase your DPS and up your kill count, and buffing the enemies to make sure your units always have something to do.

I do have a few nitpicks about the experience. First, it's almost impossible to tell what the bonuses are for enemy kills or internal production -- those are only ever shown in numbers attached to the icons which zip at high speed toward your banks at the top of the screen. It would be preferable to have those pop out in a static death animation rather than trying to view them as they move, or perhaps to have a compendium/tooltip which lets you see your earnings without needing to kill anything. Second, the unit scaling goes from nearly-free to stupid-expensive with frightening speed -- it's almost always either crucial or pointless to buy the capacity upgrades, because you're either filling out that capacity instantly or waiting for minutes+ to afford a single additional unit. I hope that the full game balances that out in the post-demo content.

That said, this was the fun and relaxing experience the game promised, worth my time.