Hmm if I understood correctly campaign awfully looks like it was in warzone 2100. You start on your original base, and as campaign went you required to move base of operations and expand with map expanding and all you built intact. Would be interesting if there was some alien based tech like in ...

My sugguestion how to make belt stack items and be somewhat readable and useful only for belt delivery.
What if stacking worked like train block signals. So each underground belt or splitter made a block, and exit of splitter or underground belt defined general stack size of items on belt, up to ...