You realize you were describing a ponzi hyip, right? No serious ICO would ever guarantee exponential returns on investment, and secondly, no legit investment would ever require you to refer individuals.
These are simple red flags to look out for, once you see those kinds of promises, don't waste time looking for legalities or due diligence. Just ditch them and if possible mark them for scams so others don't fall for it.
Assuring high ROI is really one big red flag. You can't be so sure how your project will perform in the market especially when we are talking crypto investments.
I have seen in the masternode projects giving you 1000+% ROI, and that's their main attraction.
This will only be true if the project will do good in terms of actual development and have active traders. Else, they are just for easy money of the dev.
And though referral is not really a bad one but it should not be a requirement per se.