That's a really stupid chess variation IMAO.
Helpmate puzzles

I like helpmates. They are a nice change of pace from regular puzzles. A variation of helpmates are puzzles called series help mates. Only one side moves for the entire puzzle, then the other side gives mate.
Hello everyone.
I'd like to introduce a new kind of chess puzzle, where both sides work together to checkmate one of the kings. It's like if the same player controlled both colors. In such puzzles, you can make any move you want with every single piece on the board, woth very few restrictions:
-The turn-based play is still obligatory: 1 move by white, then 1 by black.
-None of the sides are allowed to make illegal moves, like in regular chess puzzles.
Here's an example, try to solve it. NOTE: I can't post it in puzzle format, because if I do so the computer will make one of the sides' moves.
Black to move and helpmate in 3. Note that white's 3rd move is marked as 4.??? but it is actually the third move.
Later I'll give the problem explanation. Good luck and please don't see the moves list.