Elden Ring: The Speedrunner's Guide to the Lands Between.

When Jack Conners took a no name streamer's challenge to Speedrun the game faster than they did, the last thing he expected was to be Isekai'd to the world of Elden Ring as the Tarnished, with Queen Marika the Eternal as his System Admin to boot. Well, since he was already there; he might as well Become the Elden Lord and start Fixing the Lands Between, One Death at a Time. ... Love interests in mind are Marika, Melina and, of course, Ranni. Also yes, Marika is the System Waifu. — Description from novelcodex.org