Looking for a short story about a man who is visiting a planet where you get your position/job through playing a game

I read this story 8-15 years ago in German. I'm not sure but I think the book had 2 short, totally different stories in it.

The story was about a man who was sent (I think kinda forced to go) to a planet where he should play a game everyone on that planet plays. I think the goal was to beat their leader and conquer the world like this?

The better you are at the game, the higher is your position in the society. I remember that at the end he was playing against the leader and they had a long back and forth game, but I'm not sure who won.

They played the game on a different planet that had only one stripe of forest around the whole planet and a fire that goes around it. But thats only the location they were playing.

The man was chosen because he was the best player in every game if I remember correctly.

The game was a board like game where you have troops or armies that you move around. It was not an easy game everyone just could play.

Answer

That is certainly The Player of Games by Iain M Banks, the second of his Culture books, which has all the elements you describe.

To quote Wikipedia:

Gurgeh lands on the Empire's home planet of Eä, accompanied by another drone, Flere-Imsaho. As a Culture citizen, he naturally plays with a style markedly different from his opponents, many of whom stack the odds against him one way or another, such as forming backroom agreements to cooperate against him (which is allowed by the game's rules). As he advances through the tournament he is matched against increasingly powerful Azad politicians, and ultimately the Emperor himself in the final round. The final contests take place on Echronedal, the Fire Planet, which undergoes a natural conflagration fueled by native plants that produce huge amounts of oxygen. The final game is timed to end when the flames engulf the castle where the event takes place, symbolically renewing the Empire by fire. However, faced with defeat, the Emperor orders his men to kill all the spectators, and then attempts to kill Gurgeh, but he is himself killed by a shot from his own weapon, deflected by Flere-Imsaho (who later refuses to tell Gurgeh if it was coincidental).

It's a novel not a short story, but it's a relatively short novel by modern standards and could have been in an omnibus volume with some other work.