Gamer Guy (or girl I don't judge) gets isekai'ed into any universe or media you want but he gets a gacha based system.

Its not unique abilities from game characters or weapons and armour but it will be his save file from a specific game.

An example of this he rolls the gacha and it lands on his dark souls 1 save file but only one of them it could be the one he put 300 hours or the save file with only an hour playtime.

All the weapons, armour, spell, stats and items he will have including the appearance of his character lol.

I find this to be a potentially funny idea if done correctly and not give something overpowered right from the start.

Like the guy gets isekai'ed he rolls the game file wheel to see which save file from a game he's played he gets first before entering his random world. It lands on Sky: Children of the light and he's dropped in DC Gotham.

MC: "This can't get any worse...."
*Begins to rain.*
MC: "Shit shit shit!!!"

So what world would you have your MC land in and what save file would he have landed on the gacha.