Not a bad idea, at least for the beginning. I never heard IFTTT before. Just checked it. May work. So the idea could be:
- There is a bot that randomly texts a message in a Signal Group that one or all users shall send a picture now.
- The group may have autodeletion of the pictures (after 24 hours).
Limitation:
- No "Double Picture (at same time)"
- There is no measurement by software if a picture is too late
- There is propably no direct notification only to specific users.
- There is no gaming thing where you get credits, when you are on time.
So you know what real people are doing and what fake people are doing.