There can be an upgrade in the Saving Beacon like... well, I am not a native speaker... so, something like "Get connected with... Terra(?)" - a base planet. They will send the Odins drovings to the player, and he can build a poverful mashine and, maybe, get into it.
And here you are: you have the optional extra scenario: Terraines will set you on mission: go and destroy those permanently infected Walls in the right low corner.
Zergs will set a few Leviafans to patrol that area, player need to come and fight them in order to get to the walls.
There is a place for another upgrade: message exchange with Protosses, and one more technology: something like their secret "Inferno Striker" to mount on Odin.
They can ask you to go through the cave in a previously desinfected wall and save an artefact from the Temle. Or just to make sure it is there, and they come and pick up the artefact and save you.
Just some ideas, to help you to keep creating nice games)
Edit: as a result of desroing Walss, we can get some Zerg technology and Odin will regenerate slowly now; which helps in a future battle for the Protoss Temple.
And here you are: you have the optional extra scenario: Terraines will set you on mission: go and destroy those permanently infected Walls in the right low corner.
Zergs will set a few Leviafans to patrol that area, player need to come and fight them in order to get to the walls.
There is a place for another upgrade: message exchange with Protosses, and one more technology: something like their secret "Inferno Striker" to mount on Odin.
They can ask you to go through the cave in a previously desinfected wall and save an artefact from the Temle. Or just to make sure it is there, and they come and pick up the artefact and save you.
Just some ideas, to help you to keep creating nice games)
Edit: as a result of desroing Walss, we can get some Zerg technology and Odin will regenerate slowly now; which helps in a future battle for the Protoss Temple.