bug: when you save, quit and load, when you upgrade, all the upgrades you get on the same level is purchased, but if you got some higher stuff, they are deleted.
easy way to survive and make a lot of cash: get only drones at start with all money. upgrade to prawns. get two generators which will boost your cash. mass up prawns, you won't be hit anymore, when that happens, mass up generators (easy to do since they regenerate their cost really quick) then get mines near you. the enemies will slow down greatly and die near your mines ^^
an idea about the boss missions, you always need an entrophy alien since the battle lasts 2 turns.
corpsekings would be a good idea too, since they repel enemies. and some anti rangers like dark dragons would easily counter the ranged units who mess up with your corpsekings.
on the beginning of the game, even if you get an artifact, you won't be able to collect 100 gold easily. it will take you around 4 jumps. since you give all the money you collected in 4 jumps for only affording one (and even the half of a jump for the second purchase) it will be impossible to upgrade and you will pay more and more (and, you lose.)
 "Endless Migration 2 DEMO"){kind=icon}
 "Sands of the Coliseum"){kind=icon}
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 "Feed Us 3"){kind=icon}
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 "Kill the Heroes"){kind=icon}
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 "War of the Web"){kind=icon}
 "Turtle Dreams to Fly"){kind=icon}
 "Dead in 60 Seconds"){kind=icon}
 "El Fuaaa!!"){kind=icon}