the Purple Planet for [5e]

Saving Throws
Fortitude becomes Constitution (or Strength, if applicable)
Will becomes Wisdom (or Intelligence, if applicable)
Reflex becomes Dexterity
Anything that doesn't have an immediate correlation just use Charisma and if the players question it just wave your hands in the air, adopt a spooky Scooby-Doo villain voice, and say "it's weeeeird man!"
Increase all DCs for Purple Planet mushrooms, plants, and poisons by +5

Kith
Double their Hit Points, but leave the stats the same. Kith are worth 200 xp.

Death orm
They make four attacks per round with their paddles and no longer make a bite attack. Increase the paddle's damage to 1d8+3. Anyone struck by a Death Orm's paddle must make a Strength save vs DC 17 or be swallowed whole. Death Orm are worth 900 xp.

Survival
Non-native characters take one level of Exhaustion for every day of exertion under the dying sun. One level of Exhaustion can be healed by taking a Long Rest in a well-shaded and hydrated area. If a Short rest is not completed in the shade than the character receives another level of Exhaustion at the end of the rest. Dehydration rules should be followed strictly. Long and short rests follow my normal 5e house rules

Moon-milk of the Tiger Mushroom
Drinking one pint of moon-milk heals all Exhaustion levels lost to the werdling sun, and grants a temporary +2 to Strength and Dexterity (until the next Short Rest).
Partaking of multiple pints of moon-milk grants multiple bonuses, but risks toxicity. Each additional pint after the first grants an additional +2 to Strength and Dexterity but the PC must make a Constitution save vs DC 10 or take 1d12 damage and be rendered unconscious for 1d4+1 hours, for each additional pint the save DC increases by +5 and the damage increases by +1d12.

Greenstone shards
One greenstone shard can impart 1d10 charges to a lesser relic, or a wizard can use a greenstone to power his spellcasting (grants advantage to a spellcasting roll). Either use burns out the greenstone shard and reduces it to ash.
Casting mending on greenstone shards acts the same as described in Peril on the Purple Planet.

True Greenstone
Melon-sized crystals of dark green, a single greenstone can be broken into 5d20+50 shards. Using a greenstone to power a spell automatically turns a spellcasting check into a natural 20 roll, but it burns out the entire greenstone and the wizard must make a Wisdom save vs DC 30 or suffer 1d3 corruptions.

Corruption
Because corruption doesn't normally exist in a 5e game, while on the purple planet any spellcaster is subject to possible corruption. If a spellcasting check is made and a natural roll of 1 occurs, or if a saving throw is rolled against the caster's spell and results in a natural 20, then the spellcaster suffers 1 corruption. Spending inspiration cannot prevent this. The roll is 1d10 minus the spell's slot level plus the caster's Charisma modifier. The level of the spell slot used determines the level of corruption: 1-3 = minor, 4-6 = major, 7+ = greater
Having an active familiar will still negate half of the corruption effect


maybe I'll add more later, but that's all I've got for now