Set by a person or creature
These traps were created to show or stop the player from advancing. Example trap: Arrow trap! To avoid roll > 14 otherwise 1D4 arrows are sprung dealing 1D6 damage
These traps are not created by anyone but nature.
For example, quicksand! To avoid roll > 16 or stuck for 1D4 turns.
Mysterious forces cause players to deviate from their chosen path. For example, a portal opens up and pulls in players dealing 1D6 damage and teleporting them 1D4 tiles away. Players must redo that turns.
If the game had a game master then these events can be used to guide players and a better (or worse) path. A teleportation trap is especially useful in doing this.