Trickster Online is a Korean MMO released in 2003, though didn't get an official English release until 2007. It's very much in the same vein as Ragnarok Online, with the top down grind-heavy gameplay with 2d graphics. Separating it from RO is the fact that Trickster Online uses fully 2d graphics rather than early 3d backgrounds, and it is much more lighthearted/silly in tone compared to RO. Also, at least early on so far, it's so goddamn bright and colourful you may want to wear shades while playing it.
Servers were shut down in 2014, but there are a few private servers active. The one I've been playing on, LifeTO, seems to be a solid server that's decent exp/drop rates and doesn't seem to have any pay to win stuff. Which honestly probably makes it better than the actual retail game was. Info on the server and how to install it is available here:
https://lifeto.co/ (https://lifeto.co/)
You got your usual tank/magic/melee/ranged classes, but they're all a bit weird. You set your stat distribution when you make the character, and they keep automatically increasing in that amount when you level up. Each level you also get 4 bonus points to put into any stats to customize a bit, though I don't know if you can respec these at all. I'm sure I'm gonna fuck up a character as I can't find a good guide, but oh well. At least the standard growth covers the important stats.
Fun simple silly grinding MMO, I'm liking it so far. Also the "charm" group of stats is the tanky type stats, and so the cat girl Model class is the premier tank. That's kinda weird.
As an addition, with the LifeTO launcher you can select options for resolution outside the usual 800x600 and 1024x768 options, however this game be old and sprite based. Because of this, larger resolutions show more "area" but don't actually scale ANYTHING up whatsoever, including the UI. There are workarounds for this, but they seem messy and involve either batch files, registry edits, or both. So you could put up with tiny ass visuals, or run at fullscreen at a low res (making alt-tabbing more annoying), or find another option.
What I've been using is "Lossless Scaling", which is a paid application on Steam. Didn't really want to use it when others mentioned it before, but it is very good at what it does. Leave Trickster Online in windowed mode at a smaller size so the UI is the correct relative size, then with Lossless Scaling open you use that to scale the game. It'll then be full screen, but the UI keeps the same relative size. You can take a look at it here:
https://store.steampowered.com/app/993090/Lossless_Scaling/ (https://store.steampowered.com/app/993090/Lossless_Scaling/)
It uses black bars to fill space, but if you put a resolution into the LifeTO launcher that matches your aspect ratio it'll look perfect when scaled up, and handles alt-tab just fine. I use 1365x768 resolution. This is basically 1024x768, but widened a bit to fill a 16:9 screen.