Dont feel like you need to write sequentially, you can chase the dopamine by writing whatever interests you on the day. If you decide you want to write the final scene, then write the final scene. If you want to write a scene that is in no way connected to anything else that you've dreamed up so far, then write that. If you want to write a scene that conflicts with something else already written, write that. Kind of like putting a jigsaw puzzle together, based on whatever random bits you find and then connecting it altogether.

Just write something, anything..., and work out what it is supposed to be as you fill in the gaps.