Wonderful and fun game! I was wondering if there's some "losing" mechanic. A commenter below suggested if an enemy walks through your (blue) portal, something happens, but I've let enemies do that, and they just disappear into the portal with no consequence (maybe credit is lost?). A few more observations (for players): 1) Someone below mentioned tabbing out pauses the game. But if both the game browser and your other app are not maximized, the game continues. 2) The repair drones become less useful post-end game (after 3rd boss) as the range enemies kill your non-range machinas before they have a chance to be repaired. 3) I do just fine with a mixture build (all machina types except the repair drone). I'm beginning to favor the Rifle and Scout combo. 4) Increase the electrolyte buff (rifle machina) as early as possible for faster resource collection.
How far have people gotten? I've gotten to Threat level 5.0 (part of that time was just letting the game play on its own). But at that point, the TTK is low-ish, so I've restarted several times in pursuit of the 10000 kills goal.