Go on the Left stone and jump left. This should unlock some hidden blocks. Start jumping right and move along until about half way across and the blocks will stop. You will then need to jump from the last block and time correctly to hit the flag in mid-air.
It would be a nice feature if you could take your team from one of the other missions into the survival mode. Obviously limit them to level ten or their level 10 stats and weapons. Could make it more enjoyable than 4 randoms with random weapon choice.
Great game though
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