ICOSE. My ICRPG, OSE and a pinch of 4e System



Just sharing this for people like me that like to take ideas to make the system that suits you.

Some quick background. I found parts of OSE Advanced Fantasy and ICRPG Masters Edition PERFECT and other things bugged me, so I just melded the two.

I keep the use of HD for PCs and Monsters from OSE because it makes everything so streamlined. OSE Advanced Fantasy ad basically all 1e/2e and most 3e D&D monsters can be dropped right in. Converting 5e monsters is easy as well if desired.

PCs start with more HP because it is also used to activate Powers (spells and what not). A magic type character is going to burn through HP casting their spells (Powers) while a martial character can save their HP to soak damage and use their HP occasionally to unleash a special attack.

I use Powers instead of more Loot because keeping track of up to 20 pieces of Loot per PC is just a chore, especially for a mostly solo player like me. It also is hard to accept PCs running around with 2-4 swords, 2 bows, a staff, etc. Just me.

I allow assigning dice to Melee, Ranged, and Power so you can have a true classless system and make the PC you want. A “fighter” can have d10 for their melee and use the d6 for their extra Power effects.

I use Power because it works in all genres, unlike Magic or Spells. It’s weird to play a Star Wars style game and refer to Magic effort, so it’s just Power.

I got rid of Hearts because they are too clunky. Traditional HP allows for more nuance and lets you mow through things like 3 HP minions in OSE, while also being able to have a 15 HP boss that can take an extra hit.

I LOVE rolling to cast and the idea of boosting spells (Powers) so you’ll see that stays from ICRPG.

Base Powers are always moderate in their effect. Each HP spent to boost them adds some extra effect. So your Magic Missile does Power damage at Far range for 1 HP, but you can add another target or a damage die by adding more HP. So there’s TONS of freedom to use Powers in unique ways (just like in fiction).

I could type more but I think most of you can figure it out and take what you want from it.

PDF Version

My TN Cards I use Trivial and Impossible as well because they are used in the the Encounter Builder Cards that I use in solo play. They are fantastic. It also allows for more nuance, want to bullseye that Ogres eye, roll Impossible.

Ranger PC One of the 4 PCs I run in my solo games, he befriended a wolf in the Cragmaw Cave. Figured seeing a character sheet would help some of you see how Powers are built.

Sample Monsters I made, using OSE/ICRPG principles. They are made to fit on 4x6 index cards.


Sounds good, but it looks like all the links are broken, can you check them please ?


@mavfan21 I know I’m 2 years late to this but I just came here for this exact info! Is there any chance you might share the documents you had originally posted? They seem to be broken or restricted.


I as well would like to see the document. I have been looking at a lot OSR stuff, but keep coming back to ICRPG. Knave 2E seems promising though.