Say at the beginning that you can move both ways soon enough!
Thinking about a whole game centered on that mechanic made me stop playing it... Luckily the comments pointed that out, but make it clear into the game :)
Nice phone/tablet game, but it become too hectic too soon. What about some "stages", just to give the player a little pause?
Moreover, it need some more longevity. Maybe make more humans to infect, with once one dies, you go to the next, but the cures are more and more effective, as the humans realize is an alien infection.
Good idea, needs polish :)
Just my 2 cents
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 "NONDEVICER"){kind=icon}
 "Alien Infection"){kind=icon}
 "Deep Sleep"){kind=icon}
 "Space is Key"){kind=icon}