Instead of else, just copy the conditions and invert them.
For different endings, just make a number variable named "Ending"
Once the condition has been met, set the ending to ending 1, 2, 3, ect.
Once the end of the game comes, if the ending is 1, play ending 1.
I don't understand what perspective the game is being played in but it sounds like it involves animation.
These worked perfectly except for number 1.
I did this:
Enemy variable: Action = Jump
Event: Enemy compare variable > Action = Jump
Action: Simulate platform control > Jump
But the enemy doesn't jump. It just sits there.
On a related note, I did this for the boss to make it shoot:
Bullet has bullet behavior
Boss spawn bullet
Boss set angle toward position
But the boss shoots the bullet backwards instead of forwards.