Help Please Help for executing level ideas

If you have a level idea but don't know how to execute it to become a playable level, you can post it here so that others can help/provide bits of advice.

I recently had an idea of recreating the 'Red light green light' game (after seeing @Denis Nazin's Traffic Light) I have successfully created the mechanism for switching between green and red light, but I still have no idea how to force B to stop moving when red light is turned on (when B moves during red light, he dies like in squid game???). Any help?

Spoiler: Card

 

If elevated eye is activated, B will be forced to stop as we can't tap on a new block, but the problem is players can just tap on the win at the start of the game...

I've also thought of elevated zappers, but I can't think of a way such that:
* When B stops moving during red light, the elevated zappers won't zap him

 

Yep, you are right. I copied it from @MekoramB's level.

 

Thanks very much! I will investigate further on it