I can only say this (PROMISING).
Spoiler
The system goes like these:
There are Magic, Runes and the typical cheat that a novel need to differ from others SAGE.
Until now there's not magic or rune explanation only SAGE and sage explanation is that it a kind of Magic (mythical thing) that is developed depending on what were you doing or achievement you got in live, since our MC is a Pro G** I mean Pro-Gamer with a really good Avatar (Kalsted a warrior type avatar with the blood of a dragon) with many histories going around his avatar that have so many fans that where crying, panicking and laughing at him, probably because of that he developed his SAGE named (Immortal Warrior) and was picked by a Valkyrie and bring to ASGARD!!!!!!
I'm reading chapter 3.2 and so far is really good, cause is not overly saturated with created fantasy things, well, in the form that is based on Valhalla and Asgard etc. Etc..
(Sorry if you do not understand my review, I speak Spanish and I'm not confident in my written English)