In this level, your only goal is to collect 45 Energy Crystals. The problem is that the level is infested with slugs and rock monsters, both of whom eat energy crystals - and when they do, that crystal's gone for good. Since the level has a finite number of crystals in it total, it's possible to lose so many to the slugs and monsters that you can't win.
Slugs only start appearing when you've collected around 10 crystals, and Rock Monsters only start appearing when you drill into their caverns, thus you can take your time preparing your men and your base before the carnage begins.
Note that your oxygen runs out *extremely* fast in this level. If your Support station is destroyed, you may run out of air before you can rebuild it.
Strategy 1: Stealth
First build a support station, and then surround your base with electric fences. Once you have done this, you can start drilling on a large scale. It doesn't matter where you drill, but be aware that there are rock monsters that will eat your crystals. So it is best to get a small digger and dig the right hand side (east) wall. You should give half of your rock raiders weapons (or all if you collect enough crystals to have a couple of transport trucks).
The crucial thing with this level is to never allow yourself to have 10 energy crystals stored. This is necessary because once you get 10, the slimy slugs come and then the difficulty level increases by a large amount. The basic idea is to switch off "collect energy crystals" on your priority list, manually tell your rock raiders to pick up crystals, and drop them inside the protected area of your base. Then, once you have collected 45, switch energy crystals back on as first priority, put your rock raiders on red alert and then defend against the slugs until all 45 have been deposited.
Strategy 2: Defense
In this strategy we face the slugs head on, rather than trying not to trigger their appearance. Teleport down the maximum number of men. As they appear, check that each one can hold four items (by hovering the mouse over them). Upgrade the ones that can't (you may have to upgrade them twice). We want all of our raiders equipped with a drill, a shovel, a pusher gun, and a sonic blaster. (Slugs are immune to lasers and freezers)
As soon as possible, start drilling the walls surrounding your base to collect some ore and crystals for a support station. Build the support station and surround your base with fences. Your base is now protected against Rock Monsters and we basically only have to worry about the slugs. We won't be building anything else.
Now, teleport in a Small Digger, and a Small Transport Truck. Go into your priorities, and turn off ore collection and shoveling. Turn on action stations, and leave them on for the entire rest of the mission. Open up your map, and leave it centered on your base. Men on foot will stay in the base when action stations is on, but men in vehicles ignore action stations. We're going to dig around with the Digger, and if all goes well, the Transport will automatically fetch any crystals we find (and only crystals, since we turned ore collecting off) while everyone else sticks around to defend the base.
- You don't have to go get another sonic blaster after using it, they're infinite. Don't hold back. Spam them constantly. Turn your base into a 24 hour disco rave party.
- Keep your map on your base and learn to read how the battle is going by what the red and yellow dots are doing. Hop back when necessary and drop a few (dozen) sonic blasters.
- Don't dig constantly - once you've uncovered a couple of energy crystals, head back to your base and let the truck collect them all. First of all this gives you time to focus on defending your base, and secondly if you leave loads of crystals lying around, the rock monsters might get them.
- There are big patches of crystals hidden throughout the level, try to remember roughly where they are.