There should be some planets made of unbreakable blocks. These planets would have one entrance to the center, straight down. The core would be filled with rewards and valubles, which would be guarded heavily on the surface and in the core by tough enemies and maybe some other limiting planetary conditions (no oxygen etc.) Tell me what you think!
Maybe some high teir tools could break it, but the pointis to be hard and to find the entrance to the core
Well, it could be inside the core. Perhaps remove a power source and the planet would become destructible?
Small, immense gravity, populated by energy based lifeforms on the surface, riddled by electrical storms. The interior is made of the same material as outside, but eventually reaching a liquid state that can be collected, but it is difficult to acquire the proper tools to harvest. The liquid material would be impossibly hot, enough that you'd need special protection to even approach it. There may be some sort of singularity in the very heart of the planet causing this strange, anomalous planet's existence.
I don't see why you'd do such a thing as an indestructible planet, in a game that one of its main attractive is it's deformable terrain. I do, however, understand the devs/custom map makers will sometimes want to disable the mining/tier destroying feature, but using unbreakable material will be a major turn on. Perhaps when you enter this planet you're unable to use your mining tools due to interference?
The point is to find a weak spot, and make your way to the center of the planet... Why you ask? well people have already posted some ideas of what to put at the center... each one would have a special surprise inside, maybe in game currency or rare equipment...
The surprise should be a treasure room. And there should be a 10% chance that when it is generated, it is a Death Room. The chest is full of really valuable stuff, but the walls are mad of a thick indestructible stuff, and when you enter, the door slams shut and a spike plate descends from the ceiling.
Nah, that is a dick move. But a 10% chance of a boss ambush (with a prize at the end, better than usual) would be great.
No player should ever be trapped in a no-win situation. If traps of this sort are introduced, there should always be a way to escape them. Otherwise, it would just ruin the fun. Escape should be available in the form of a hidden switch, an emergency override, a hidden enemy operating the trap, a puzzle lock, or a discreet section of damaged or poorly-constructed wall that can be broken through.
