i have never participated in gamejams before, i wanna ask that when i submit my game is it gonna be optional for others to try my game and my game might be played by absolutely no one? also are engine's 3d objects allowed? like the cube, capsules etc? in godot theres "csgboxes" and its going to be hard to make the 3d world without them..

Heya, your question is covered in the Rules & FAQ :

❌ Not allowed

• Models, textures or other visual assets that are bundled with the game engine

Both Kenney and me have packs that include 3D primitives (cubes/walls/capsules etc.), you can use those instead