I see this as a 2D top down puzzle game.

The idea is that there's some liquid resource, and you have to move it from one place to another. To do that, there's typically some source, and then you have a bunch of units you can use to carry it.

The issue, though, is that carrying the resource in a unit, consumes the resource. Units, without the resource, can't do anything.

So, you can, say, pickup some resource at the source, move it a bit to the next unit, and give half of your reserve to them. But, you have to have enough to get back, since otherwise you can't get to the source again, and are probably screwed. Then, that unit needs to have enough that they can get to the goal without having spent all their cargo in the process so they have enough left to get to the target amount.

That's the rough concept.

Other twists:

• Static Pipelines
• When the resource is put in one side, it is deposited at the other side, allowing transfer of resource across distances without carrying it.
• Perhaps these distances are even impassible to the units
• Cisterns
• These are static holds for a limited amount of resource
• One can deposit here to either build up an amount, or as a transfer point between units that don't have to physically meet
• On some of the harder levels, there might not be an infinite source, but just a cistern. In these you'd have to make it in a certain number of steps so as to not run out.
• Gates
• These require some resource to open, so a unit must give some to the gate in order to move beyond it.