The Wonderland Board

The attached image mostly speaks for itself.

The UFO closest to the powder keg storage is killed by standing in a certain spot. Then, the barrels are set up. One extra barrel is placed near the first box to blow up the way inside, then the box on the outside is used to redirect a UFO into it.

Obviously, you can get all 13 bonus coins with this solution. Deluxe W4L4 is now a level that can be solved without a single rainbow coin. It takes longer, so it's not really a shortcut, just a fun little thing you can do. In this solution, Peegue does not go through the plot-mandated exit.

I love seeing crazy things like this in games - thanks for showing this off, Muzozavr!

In a similar vein, there's a trick route I discovered a long time ago in Secret Worlds on "Kaboom! Cave": http://www.pcpuzzle.com/forum/viewtopic.php?f=1&t=27709

In that same level, you can also make all of the Kaboom!s explode in the first room if you make the exact right moves.

EDIT: Oh wait, you commented in that thread already... silly me.

Anyway, now with this level, the Deluxe set of RTW has its own "ignore rainbow coins" possibility. The Platinum set has level 6, WSW has "Kaboom! Cave".

If there's anything in the classic set for RTW and in the original first game, then all official levelsets will have one "bypassable" level. (It might not work out, though)

I just recently solved this level like this, but I forgot about the wood box near the top left and instead I found a way to replace the steel box in the conveyors with a powder keg and used that to redirect the UFO.