@c5bffeca I roll a 14, 8, and 5.  You roll a 6.  My 14 fails. My 8 is higher than your 6, it’s a hit! My 5 is lower than your 6, so even though it’s a successful result, you dodge it.  

A million variations: critical success when you hit the target exactly, automatic successes when your target is >20, etc, but it’s fundamentally a very simple system.