How to change the tickrate

[Ivavmak]

how to change the tickrate of the whole world, while making the player move at normal speed?

[ChampionAsh5357]

No such thing since all entities are ticked using the exact same process for ticking. You would need to rewrite a good portion of the game if you wanted to do this with no game breaking bugs.

[Ivavmak]

Is it possible then to slow down all entities except the player without changing the tickrate?

[ChampionAsh5357]

Again, same issue. A player is an entity, so it would be slowed down as well. You could force an entity only to tick every other frame, but then that messes up animations. You could also change the movement speed attribute to make them move slower, but that only works on living entities and doesn't affect their overall logic. Another way would be to increase the player's attributes, but that's probably the best you can do without rewriting a portion of the game logic.