In my last post, I re-blogged a post Thoughts on Critical Hits & Fumbles in Old-School Games — Smoldering Wizard; original post Thoughts on Critical Hits & Fumbles in Old-School Games — Smoldering Wizard. Depending on the Role-Playing Game (RPG) as to how critical and fumble are handled. My favorite was Iron Crown Enterprises (ICE) – https://en.wikipedia.org/wiki/Iron_Crown_Enterprises way of handling critical and fumble rolls. The system used percentile dice with a range of 01 – 100. If you rolled 01-05, it was a fumble; if you rolled 96-100, it was a critical. However, the approach was you rolled again and if you rolled 96-100, it was subtracted from a fumble and added to a critical until you stopped rolling 96-100. It was rare you got a third roll as rolling 96-100 only happens 5% of the time.
It tended to get not too messy if you had either a fumble or critical roll without getting a 96-100 roll when you rolled again. I don’t have the rules handy, but most of them with only one critical or fumble roll weren’t usually too bad.