because mars once had an active core I think it would be interesting to add a mars version of the nether. how do you get to it? you need a new schematic for a bore drill. this would be very expensive to make and it would require a lot of energy and time to use. what does it do? it drills a hole in the bedrock of mars. looking down the hole made you can only see more bedrock going into darkness. if you attempt to enter the hole you will die. how do you go down? you build a lift that will take you down safely. once in the mars-nether you may find new mobs, ores and plants. you will find small quantities of packed ice scattered around. and massive "seas" of a new block- hardened magma which could be smelted for normal magma blocks. perhaps you could find Martian villages or giant Martian wasps that attack with poisonous projectiles. maybe even a new dungeon. I think this would be a good idea because it encourages players to go back to mars latter in the game. it could also add variety to the line up of dimensions added