Playing a tower defense as the monsters sounds cool on paper, but I don't think you've managed to pull it off here. Your minions are way too squishy and after you've bought your second portal, the game just stops.
Viewing post in Last stand jam comments
Yeah... I blame it mostly on the missing features. Summoning portals should have been upgradable to rise minion statistics or just plain out change the minion. Also, a lack of real obstacles in random map generator (something akin to sandbags around solders) made things worse, because there is no real tactic to portal placement. The game is either to easy (blobs of minions charge closest helpless solder) or to hard (minions are sniped before having any real chance).