I don't use a timer for my arcade racing game runs because the game itself count the total time, no need for an external timer normally.

The actual game time should be the only time that count, not a total game time from an external timer.

Unfortunately due to how setting up boards work the default timer is a global setting. Since RTA is set as the default for the board all categories use RTA as default. The only fix for this is to leave the RTA field empty on all the Arcade runs which would then sort by IGT. It would be worth bringing this up with @Naegleria so he can just manually remove the times from currently submitted and future arcade runs

i also run Daytona USA 2 Power Edition, and the moderator only go by the game time, as any arcade racer's times should be on this website, not the external timer.

It can be set to have one or both, but it would apply to every category. For Arcade, gametime is fine; for 10 Year Championship, you could change car settings in between each and every race to get slight improvements in game time with large losses of real time. Gametime would be useful for cross-platform comparison in 10 Year, realtime would be better for the same platform.

Edit: I switched the leaderboard to sort by Gametime.