FATE. Designed to be about the simplest thing that could be called a system, but endless flexibility in what you use it for. The Accelerated version is about 40 pages, the Core version is a more detailed, but still less than the typical RPG rules set.

The system is designed so that the players can influence the events of the game at the cost of increasing difficultly. For instance, every character has a High Concept, such as "Best swordsman in the kingdom". This can be used by the player in many ways, such as celebrity notice, justifying related skills, background, etc. but the game master can also invoke it for things like bitter rivalry, getting conscripted or not being able to go incognito.

As such, the system can work at many different levels. One popular setting has characters as magical cats, another as post-human cyborgs. And it all works.

For a list of various settings: https://www.evilhat.com/home/fate-worlds-and-adventures/

Isn't #2 solved by a good Dungeon Master? The DM should be able to take control of the game so that players aren't just going around killing orc babies. "In the distance, you see a group of 1000 orc parents coming searching for the killers of their babies..."

I don't like too much explicit intervention by the DM.

Part of it has to feel like the player to feel like there are fair predictable rules that the game adheres to. Yes, the DM has to step in to make sure the game feels good, but the extra work to combat game mechanics doesn't feel like a good use of the DM's time.

Your solution is a good, creative one but I don't like that poor mechanics got us here.

If you play dnd like #2, the solution is a new gm/group, not a new rule system... that said, I'm not a great fan of level based games, and really do like White Wolf's Storyteller-system. (vampire the masquerade, mage the Ascension).

But like with any other rules I've seen - it requires some discipline and agreement to not stray too far into the rules part. Rules are just guidelines that help avoid the worst of: "Bang! Bang! You're dead!" ; "No, I'm not! You missed!"...

No rpg rules are complete enough to form a full simulation - any attempt to do so will likely sap fun out of the game. They're just a helpful frame of reference.

A lot of 5th edition adventure modules have started advocating "milestone levels" instead of XP levels. It requires a good DM to know when it's appropriate to award a level up but it's basically DM fiat leveling; XP is gone entirely and the DM decides when your party levels up typically based on the party achieving certain milestones -- find the McGuffin, defeat the boss, solve the mystery, etc. I'm running Curse of Strahd for my table right now and we're using milestone levels instead of XP and the players seem to really enjoy it.

Nice idea as long as the milestones are laid out in advance.

It’s hard to do that without spoiling the plot. Milestones should also be flexible. Strahd has more milestones than you need to reach the stated end level of the campaign. It’s a sandbox so some of them won’t get done, some will be done after the party has outscaled the encounter, some are coupled to plot reveals. But it’s not hard to manage.

Look into the Powered by the Apocalypse games (Apocalypse World, Dungeon World, etc). My gaming group switched over to them after we spent an entire 3 hour session fighting a few vampires and everyone was sick of it. PBTA puts storytelling and player agency over granular combat.