Okay, for anyone who cant beat level 25:
You need 2 perks: Improved gadgets and 00 gadget. If you dont have them, start over the game. Equip the active barrier gadget.
Then the only thing you need to do is hold "S" and nothing can hurt you.
The level 11 challenge is easy in this way as well, because you hold "S" and wait them to kill themselves. Equip the mutant body and face for faster effect.
The level 17 challenge: Equip the Anti-Bullet Field gadget. Kill the melee enemys, and if you have 3-4 shooting enemies, go to the right side. When they came after you, teleport to the left side. Turn on focus and go towards them. If you see them shootin, dash into the bullets. Teleport or dash back, and do it again.
Hope this helps a lot of people.
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