It could be done, but you'd need to change the scripts at least a bit so that when the game is loaded it combines the plots from multiple files into one in-memory dictionary/javascript-object.
You can also just split a big plot line into smaller sub-plots using a jump node (eval_jump_to). From the player's perspective this will look exactly the same, but the editor will not evaluate a jump node and simply end drawing the graph if it encounters a jump node.
I currently have a game with 19 384 nodes (the plot.txt is 3.3MB) and the size of the plot is not a problem. True, some paths are convoluted and terrible to view in the editor, but there's a 'Draw from this node' button that hides pars of the graph that are unreachable from the select node.
That game was never posted on itch.io, at least >I< didn't post it here. If you google 'SlutED' you should be able to find it either online or a download link. If nothing shows up, look for F95 zone.
If all else fails - check out my buy-me-a-coffee page (link should be here somewhere) fresh links are always in the discord if you decide to become a supporter.
I haven't used Windows XP for years now, and I'm no longer sure what can run on WinXP, but if you have a web browser that supports moderately recent CSS (variables, flexbox, grid) and Javascript (local storage, speech API), that browser should be able to run a game made with this engine ( but I expect some of the CSS may need changes to be more compatible).
In 2022 only around 0.1% of all devices run winxp, that's a very small niche and I think that for anything other than retro gaming people should really switch to something else. I have currently no plans of making the engine more compatible for windows xp than it already is.
