@HerraBRE I wouldn't do an ICO. Pay-if-not-whitelisted is a legit and should-be-tried approach to anti-abuse mitigation.
Proof of Work *may* be applicable but there's no need for a ledger:
- If doing PoW, you could try challenge-response. "Solve this specific puzzle". No distributed ever-growing database involved.
- Or use a cryptocurrency that already exists. No need for a new one.
ICO may be tempting because this stuff is damn hard to fund but I think it would probably bite you...