Players can increase the difficulty of planets by purchasing Challenge Levels with Credits. When challenge levels are in effect, enemies gain higher stats, some mutate into stronger versions of themselves, and in some cases new enemies are added or existing ones removed. Once you go back to the ship (or die), however, challenge level resets to 0 (that is, planet difficulty goes back to normal). Challenge levels do not persist through play sessions - saving and exiting on the ship resets the challenge level to 0 (no, you can't buy challenge levels for your Ironman character with a different character).

EXP & Credit drops as well as Gear Chalice rewards are boosted based on the current Challenge Level. While any Challenge Level is in effect, monsters and Loot nodes may drop Aetherlite, Darkened or Omega Shards - which can be turned into Prisms in Mech City for Ultimate Gear forging - as well as Mods. The frequency of these drops increases as Challenge Level increases.

Level Credit Cost Mod Drop Chance Shard Drop Chance
1 5,000 4% 2%
2 10,000 8% 4%
3 15,000 12% 6%

As well, when challenge level is 1 or above, most towns receive an Item Chalice that gives you an item for free, and shops begin stocking mods and selling them for 5000 credits each.

Challenge Levels are purchased at any Computer Block in series (that is, if you want to run Challenge Level 2, you must buy Challenge Level 1, then Challenge Level 2). For more information on the changes made to each planet depending on the challenge level selected, check out the bottom of each planet's page.