An example would be : An ingame simulator of dmg so that it calculates your best item in terms of dmg ( I have equipped a RIB and when I mouseover another RIB in my inv it could show me under its bonuses - whats the DPS increase - or if its is any at all - or maybe " You will do 3,4% more dmg to Undead" ( bcs the item might have low avg but 20% undead on it ) . Fuck me I'd be paying for this . And you can sell it to players (thousands) not only devs
Or maybe like steam overlay - when you press Shift-Tab for example - it opens an overlay that shows the best combos for your character - it makes a good pvp addon . And you can showcase the fluidity of your new sync position system in the videos. For example its shows the combo for dagger . Or an addon which shows a small video for best way to farm in monkey dungeons - and maybe highlights a spot where u should sit in monkey dungeon on the minimap. Hahaha Idk you do great porgramming work so the possibilities are endless - and you could make a ton.
And yeah it won't work on some highly customized private servers - but everyone plays official like either way. Who tf is interested in some shitty ass new maps with new mobs that aren't thought of my Ymir?