DND_Reborn
The High Aldwin
Like your system, when you reach 0 HP you make a Concentration check based on the damage that took you to 0 hp. If you fail, you fall unconscious. If you succeed, you can either move, take an action, or take a bonus action. You cannot take reactions.Cool! My players (in two groups now since I moved states) love the idea of being able to contribute while on "death's door" and the extra thrill. Since we use a variable initiative, it gets tense when someone hits 0. However, I'm not sold on my current way of doing things (to discourage whack-a-mole, I've been imposing "death save failures" each time you hit 0; 3x and you're out.)
Personally, I go back and forth on a lot of this sort of stuff. I want "more", but a balance with keep it simple still and not introducing a bunch of new things to the game. It is a difficult balance to achieve.