This what I have found: https://altcoinfantasy.com/
https://coinmarketgame.com/
another option is to use bitsgap for this kind of purpose. you can open up a demo account with bitsgap and then trade there. if you're fine with a little coding, then try using zekko with its backtesting feature. you'll be able to trade or look at past chart history iirc. it should give you an additional way to understand when indicators give a false signal or good signal.
Thank you for mentioning! Let me know if there are any questions about the demo or live trading in our official thread. Following the author's question, we have also prepared some educational material available in our official blog where you can find everything beginner trader needs to know. Here is the link for that.