If you want silliness and pop culture references, Dungeon Crawler Carl should do the job

Old Man’s War is a really fun, easy read. The aliens are pretty creative and the basic premise of old people getting new bodies to fight battles in space is fun.

I would recommend Ender's Game as sharing a number of themes as well as being easy to read.

'Only You Can Save Mankind' by Terry Pratchett.

Off to be the Wizard by Scott Meyer, it's a blend of Sci-Fi and fantasy. Just a little bit different.

Mogworld by Yahtzee Croshaw follows a sentient NPC unknowingly living in a video game. It's not so much wrapped up in nostalgia and is a dark comedy, but the author takes the premise seriously enough. I've read it several times. Not many books like it.

Ring World by Larry Niven is a big departure from the genre of video game existence, except that it's the inspiration for the Halo series. It's a old fashioned sci-fi romp, the kind of thing that inspired ready player one. It's got super technical cool hard sci fi concepts mixed with an extremely colorful cast of misfit protagonists. Very readable.

Random, but Mrs. Frisby and the Rats of NIMH by Robert C. O'Brien is so extremely imaginative in the way it nest it's cast of talking animals within the real human world. (Yes it is actually sci-fi). The book is marketed towards children, but that was more an artifact of how it got published back in the day. It's extremely well written. The movie is cute but takes a lot of liberties.

Well, there's the book he ripped off, Snow Crash by Neal Stephenson

If you want something with a game/tech black mirror like feeling, I recommend Daemon and Freedom by Daniel Suarez.

I didn’t read that series (referring to Ready Player One) since there was transphobic stuff the author put in the book.

But in terms of fun reading I would recommend the Monk & Robot series by Becky Chambers. It’s wholesome and heartwarming. It’s two sci-fi novellas.