If you pay fixed price for unknown outcome it should be clasified as gambling/investment and regulated. Odds should be published (if known) or past performance if known, expected value and such. Deviation from any information stated at the moment of sale should nullify the sale and give you your money back. If the company hesitates, funds should be seized immediately and put on hold until people who bought the tickets come for their money.

I have no hard rule about which kinds of gambling/investment should be completely forbidden but all should be scrutinised and some limitations should be imposed. Like a ban on advertising.

App economy is now gambling economy and at some point it will trigger heavy regulations.