I've taken a go at this just this morning. Cool to see Zeratul, I'm not much familiar with the system that you seem to have built with the backpack and items and stuff (maybe I should've played the replicant to understand) But it was quite the info to take in, and like aliencommander points out, I also had an issue where I did pick up the power cell with the major, but when I got to the escape pod a message popped up saying I didn't have it, I then put it on the ground again, picked it up with my character and then it did work.
I really liked the vibe from the planet you created. I ended up getting slingshot into the mines straight away. Am I correct in saying that there was a choice of what mission to take? The mines or the Arena thing? Because after I completed the game I went back to the editor to check as I though I hadn't seen all of the map yet.
I found difficulty during destroying those missile turret slightly easy (and yes, I just said that as probably the worst player out there) Especially because you can train quite a powerfull army with all the elite units. I didn't equip any items btw during this because I was not quite clear on them at the time.
Lastly, minor thing, there's pathing blocking even after the missile turrets are destroyed.