I’ve added collision to the NPCs and they still don’t collide with the player, what do I do?
You’ve added a collision mask that describes the collision area. But it doesn’t include collision logic, the “what-to-do-when-a-collision-happens” part. You now need to add events that tell GDevelop what to do when a collision occurs.
Here’s an example of how to do that from a GDevelop tutorial video
Thanks! Other question, is necessary add events for obstacles? for example a “tree”?
You’ll have to add events for every obstacle.
However, if there are different obstacles with the same collision action, you can combine them into an object group, check for collision with that group and apply the actions to that group.
For example, a tree, a wall and a table can’t be walked through. So you’d put those 3 objects in an object group and have actions to prevent the walking through for that group, and it’ll be applied to all tree, wall and table objects.
Here’s a video about object groups.
And here’s the GDevelop wiki entry on object groups