Another Swedish BRP-derived game, Mutant (which is the spiritual if not mechanical predecessor of Mutant Year Zero) used SIZ+CON for hit points. Of course, it had weapon damage scaled differently (although not doubled).I'm familiar with BRP-family games setting hit points to (CON+SIZ)/2. I know there were early versions where it was just CON, but I'm not aware of it ever being CON+SIZ without dividing the sum by 2.