I Became the Genius of the Gigant Academy기간트 아카데미의 천재가 되었다

That ways the best explanation I have seen

Read all available chapters (17). It's pretty decent. If you're into Mechs then you will likely enjoy it a lot more than me, but even then I still like it.

Basically MC woke up in the body of a beggar in the game he was obsessed with. Its all about Mechs and MC is clearly obsessed with them, which is nice to see. He is genuinely excited at seeing/experiencing these things and is very hardworking, since he knows that the others around him in the Academy are all extremely talented main characters of the original game.

Unlike most novels like this, MC doesn't try and take a backseat or hide in the background. He makes it his goal to be seen as much of a genius as possible. This is due to his System - it mainly offers him Quests. These Quests are almost all ones the Main Character would get in game, and thus require him to do things that a main character would do; rank at the top, become the group leader, etc.
Obviously doing this does change things from the original game, but he doesn't seem to be that worried about it. He doesn't solely rely on his game knowledge, but makes sure to confirm whether things are the same or different and then react accordingly.

There's been some signs that his body is different in some way/it isn't just a random beggar, but there's nowhere near enough chapters for that to be explored yet.

Overall its a pretty decent start.

Seriously, are novels with extra mc suddenly on the rise??? There are many within the recent mass release of novels

I made a website for orphans.... it doesn't have a home page