vargilius, yes there are blank inputs (that is to say "robots with no symbols in their tape") where they make sense (for example you could get one if you need to change red for green, but not if you are asked to move the first symbol to the back).
Also, though similar, this isn't a Turing machine (and not just because your state-set is non-infinite). In a Turing machine you can only read an write from the same place, but you can move both forwards and back along the tape.
The flamethrower seem dis-balanced (15 DPS for the 3 coins?) Also tanks should have an explicit retreat option (sometime waiting for them to get damaged takes too long)
The story is amazing, I loved how even though the AI is in deep denial it still makes the same choice as it's creator, I guess it runs in the family. The gameplay is meh though (not because it's bad, but because it's been done to death)
Seriously, all the upgrades are the same (except missiles and repair, which are missing) and in the 1 level like 2 waves were different from pixelvader, and the rest were the same, and even the boss fired in a very similar way (although this one technically moved and the one in pixelvader didn't)
MJ- Destroy the grave in jamaica (Mexico) Tank- kill Rambo in Qandahar (Middle East) Boomer Santa- Kill Santa in Nuunok (Greenland) Col.Sanders- Kill him in Kentucky (America) Ronald Mcdonald- Kill him in London (Europe)[also found in multiple other places] Venom - Kill Spiderman in New York (America) KEEP THIS COMMENT ALIVE!!
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Actually "Rambo", McDonald and Sanders can be found all over the globe, and there's a second Santa at the North Pole (duh!)