Sorry to grognard but I say play to the original strengths…there is a fairly large market to be tapped for re-doing UU, UI and all, the works ;). Or, an approximation, but keeping every mechanic present in the original.
We know this because of the numbers who expressed initial interest, and the scale of the disappointment in the reaction, and the nature of that disappointment with UA. Think of it as a (dis)satisfaction survey that gave you a lot of info, pointed mostly in the same direction.
Even just (just!) re-treading UU would sell well, if you stuck to it faithfully, warts and all. The story, the dialog, the mystery, the sleep, the water - it’s all there. It could also re-establish the franchise on a proper footing (licensing issues permitting) to the point where the chops would be there for a true sequel of sorts.
Or, as above, riff a little on design, but never to the point of water arrows etc
Personally, I think new IPs sound more enticing than they are often are in reality, because there’s so much spadework, and you’re back in a world of budgetary competition and no recognition for the IP. Why both when you have the existing titles you do? They are your gold, as good as it gets.
Otherside are premised on a number of known games which boil down to 2 - 4 ‘brands’ essentially, so you should use the heft associated with that, and those you now have rights to. WHy dilute and go hunting now, especially on a limited budget? PLus, you get to the check the ‘unfinished business’ box with UU.
A tight re-imagining of UU, or thereabouts, might also restore wider faith.
I’d actually put my money where my mouth is on this (though I know KS is now strictly out of favour) and be quite happy to test and get properly involved. I’m sure other old hands on the forum would too.
Single-player, definitely. That is what you are known for,and these games are all about.