LÖVE is great - but are there any good engines / libraries built on-top of LÖVE that make it easier to create certain 2D games?

I.E.

A top-down tile-based extension? Ideally just an integration with some existing 2D tile map editor.

Or an isometric extension?

Or a side-scrolling extension with gravity and parallax and a tile map, etc?

When I tried LÖVE years ago, it seemed like there was a little bit of engine-building before you could really start making a game. Like figuring out how to do the rendering and tiling and jumping between scenes/rooms, etc

You may find some examples in the forum and wiki, but they are community-(un)maintained. There's no guarantees that everything will work and be up-to-date with the most recent versions of the engine (I have not maintained mine, for once). A lot of people are attracted by the minimalism and the DIY approach, but I understand that's not for everyone.

If you are looking for a more "batteries included" approach, then probably Unity (with its plugins on the Asset store) would probably be a better fit.

See my post in this thread regarding Planimeter Game Engine 2D. Planimeter ships the largest pure-Lua 2D game engine on GitHub.

Features: https://github.com/Planimeter/game-engine-2d#features

We integrate with Tiled, and feature multiplayer with client-side prediction out of the box.