@MRain the difference from Gantz? Probably the MC and how the player solves the problem.
In Gantz, the MC is like a typical shounen character, like a stupid brat and somehow can succeed in the game compared to the more awesome character in Gantz. While in this manga, the MC is more critical about everything and more anti-mainstream compared to other characters in this manga which makes him stand out.
And you can differentiate how the player solves the problem of the game. In this manga, they are discussing and thinking about the game and there is an intermezzo about their personal life. In Gantz, they are just let it flow, not thinking about the game until they are in the game, and mostly dealing with their personal life like a girlfriend, school, etc.
In this manga, you know where the end game is from the early chapter. While in Gantz, I believe it in the later chapter it is revealed there is a final game/doomsday.
Summary:
This manga has a strong MC (not OP power, I mean character-wise) and a few characters, but the others are weaker in later chapters like that glasses-bullied girl and host guy. It is also nice how the mystery is unfolding after each game and they develop the answer for the final game instead of just playing the game and after that continue their ordinary life without care of the next game.