A few years ago, I was discussing P&P RPGs with a friend of mine, and I mentioned how I'd kinda like to make my own system, rather than use a pre-existing one. They thought this was crazy, and way too much work for me to pull off. I took this as a challenge. Years later, the system is nearing completion, with combat getting the kinks out of it now. One of said kinks is my counterattack system. And that's what I want advice on. If someone misses an attack, it can be counterattacked. The roll to hit is 1d10+{bonuses for skill and weapon}-5{counter attack penalty} This was added in an effort to keep combat moving faster and more interesting. But here's the question: Should counterattacks be possible to counterattack? Or should they give a penalty to defense next round? This is just a lot of rules to sort out for one guy and a friend, so any advice would be appreciated. There are some other problems I'm trying to work out currently, like how much XP should be required per level (D&D is a 1-20 game. The system I've designed is more of a 1-200/250 game. This is to accommodate my brand new skill system I designed, where getting all skills to max would require level 250.) Any advice is appreciated. Thanks