Grid Hero was a very popular trading robot which was at the top of the MQL5 marketplace for a long time. It boasted a backtest record of success between 2004 and 2017 but it failed in 2018 and 2019 wiping out accounts.
This is a martingale and a grid system and these will eventually blow your account though it had an amazing track record for such a long time.
Being a martingale and grid trading robot automatically puts this in the high risk category. These robots bet larger and larger amounts when losing in hope of a turnaround.
Of all martingale and grid trading systems, I'd say Grid Hero is one of the lower risk ones. Returns quite small but they are consistent.
Despite blowing an account in 2018, I am using this again and currently it's 20% up. I am using this with manual intervention, manually closing all positions and taking a small loss rather than let the system play out.
Grid Hero is optimised for the EURUSD pair and on the hourly timeframe. All SET files are provided by the author.