I played this game installing it from my Epic Games library using the Heroic Games Launcher.

To get the game started and running in game mode

1. Remove all the launch options.
2. The TARGET box should be the "/home/deck/Games/Heroic/GravitarRechargedRosN/Gravitar Recharged.exe" and the START IN should be the "/home/deck/Games/Heroic/GravitarRechargedRosN/" folder (including the " quotes)
3. Go to compatibility and select "Force the use of a specific Steam Play Compatibility tool" Proton Experimental worked for me.
4. To get passed the log in screen DO NOT USE GOOGLE to log in. I used my Nintendo account specifically. If it says a redirect error but you hear music just hit the Steam button and select the game (very top option).

EXTRA TROUBLE SHOOTING

1. If text is cut off on the sides then you can change the resolution to 720p (1280x720) but there will be black bars on the top and bottom of the screen.
2. If you are stuck on a blank screen with just the URL and things at the top hit the Steam button and select the game (at the very top). You may need to hit it more than once or try the B button and maybe wait a few seconds (like 5 or 6) I'm not 100% sure how long but I thought my Deck had completely froze (technically it did). Slightly Frightening I know.
3. I noticed that sometimes (Usually if you just played another Recharged game) it won't let you log in. You will just see a swirling Steam logo with the URL at the top. You will have to restart your Deck. Mildly annoying I know.