- Basic Fighter Stuff - The Fighter's Base Attack Bonus increases as in LotFP. The Fighter can also Press, Fight Defensively, and Parry like in LotFP.
- Skills - The Fighter gains skill points like a Specialist in LotFP, and can spend them on any skill except Sneak Attack or Luck (see below).
- Sneak Attack - The Fighter starts with 2 ranks in Sneak Attack. The skill increases to 3 ranks at Level 4, 4 ranks at Level 7, 5 ranks at Level 10, and 6 ranks at Level 13.
- Great Cleave (or "Unstoppable," from Warriors of the Red Planet p. 8) - When the Fighter kills an enemy with a melee attack, the Fighter can make an additional attack against another enemy within melee range.
- "Did You Just Punch Out Cthulhu?" - Once per day, if the Fighter takes no action for at least three full, consecutive rounds of combat other than getting pumped up about killing an enemy, then the next attack the Fighter makes (in that same combat encounter) will do the maximum amount of damage (based on the Fighter's weapon), stun the target for 1d4-1 rounds, and give anyone who targets that same enemy (in that same combat encounter) a +1 bonus to hit. This ability cannot be used in the same attack as a Sneak Attack.
- Fuck Psychics - The Fighter can no longer start play with psionic powers, no matter how high the Fighter's ability scores are.
- Basic Sorcerer Stuff - The Sorcerer is the only class that can perform rituals, as per Carcosa. In addition to the effects listed in Carcosa, the completion of rituals (or the subsequent bargaining with summoned entities) may sometimes lead to additional powers or rewards, at the DM's discretion.
- "I Will Destroy You With My Mind!" - The Sorcerer automatically starts play with psionic powers, and all 8 powers are available to the Sorcerer every day (rather than 1d4 random powers).
- Luck - The Sorcerer starts with 2 ranks in Luck (see LotFP Playtest Document 0.1). The skill increases to 3 ranks at Level 4, 4 ranks at Level 7, 5 ranks at Level 10, and 6 ranks at Level 13.
- Identify - Once per day, the Sorcerer can magically/psionically investigate the function of a magical, high-tech, or otherwise unusual item in a manner similar to the spell Identify in LotFP. This process costs 100 gp in materials and takes 1 full day to complete.
- Recharge (based on the ability from Warriors of the Red Planet p. 14) - Once per day, the Sorcerer can attempt to magically/psionically recharge one special item that carries limited charges (such as a ray gun). Doing so costs 1d10x100 gp in materials. The Sorcerer must roll a d6: on a roll of 6, no charges are restored and the Sorcerer must make a Saving Throw vs. Magic or else be subjected to 1 year of Unnatural Aging (see Carcosa p. 14) and waste 1d4 additional charges of the item. Otherwise, a number of charges are restored to the item as follows: 1 charge at Level 1, d4 charges at Level 4, d6 charges at Level 7, d8 charges at Level 10, and d10 charges at Level 13 and above.
- "I Won't Lift A Finger!" - The Sorcerer starts with a Base Attack Bonus of 1, and this bonus does not increase upon gaining a level, as per most classes in LotFP. Likewise, the Sorcerer cannot Press or Fight Defensively, and can only Parry like a Magic-User/Cleric/Specialist in LotFP.
- Hit Dice are d8, as per the Fighter in LotFP.
- Experience Points needed per Level are based on the Sorcerer.
- Intelligence, Wisdom, Charisma, and Saving Throws use the rules from the LotFP Playtest Document 0.1. Strength, Dexterity, and Constitution still use the rules from LotFP Rules & Magic.
- Give "Basic Fighter Stuff" to both classes and remove either "Identify" or "Recharge" from the Sorcerer to put the classes slightly more in line with Carcosa as written.
- Replace "Identify" with "Magic Sense" from Warriors of the Red Planet p. 105.
- Change how Unnatural Aging works for the Sorcerer, since Carcosa doesn't get too specific about it, if I remember correctly. Maybe replace it altogether with some other penalty.
- Change the name of the Luck skill.
- Add some new skills and remove some Old Ones. Ha.
- Give different stats/abilities to the different technicolor peoples of Carcosa.