Nothing. Literally nothing. I cannot emphasize this enough: I was actually stunned at how nobody actually wants to do anything but slap vichan or whatever onto a server and call it a day. Not a single one of the altchans I visited had any features that were not either already present here or a derivative of what's here but made worse and all of them also run software that made the baffling decision to make it impossible to turn a bunch of the extension features off. I poked around in the code for a few of them and they could easily add checkboxes for things like image expansion--lynxchan, for example, has a check in its image expansion function (part of inline-expanding.js) to see if you're holding down CTRL while clicking and which bypasses the entire rest of the function if you are, which could easily also check for an option for whether or not you want to expand images at all. You have to block or override that script yourself if you want that option. That's only one of many many things that you just can't turn off. Lynxchan and vichan and everything else like those are bloated pieces of shit, the sites running them all have horrifically ugly CSS, and the people running them love to ruin the imageboard experience with sound webms and huge walls of poorly formatted multi-image posts interrupting the flow of what should be a smooth, simple interface that never distracts you with bullshit. How did imageboards get uglier and more annoying to use as time went on? I hate tinyboard and all of its infernal progeny like you wouldn't believe. Imageboard software peaked with wakaba and it never should've gone any further than that.

The closest thing to actual innovation I've seen on any of them were the ones that update in real time, but that actually just gets really annoying to deal with in daily use. It might be a fun gimmick board here, though. Maybe it'll make up for /f/ dying.