We just released our first offering on KS called Kaiju City and we've been asked about solo play rules.
Solo play was something we had talked about during playtesting. I think the nature of the Monsters' special abilities would make an effective transition to solo play as the city with automated Monsters.
For solo play as the Monsters, you could ditch the resource tracker and draw / play 2-3 city tiles (like 3 resource or 2 resource +1 military Tile) each round and add them in a spiral pattern around the board keeping the city square to automate the City.
We could even have variant rules for Monster Battle Royale where the monsters fight each other as they are being attacked by an automated city.
The real question is, how valuable would this be to the players / potential purchasers of this game?
Let me know what you think!
To me, anything that adds value without adding complexity is a good thing.
So I would say yes, this is potentially something that may convince somebody to chip in that wouldn't otherwise.
The real question is, how much would it cost you to add the ability to play solo in. If the cost is negligible, then i'd say go for it.
All this is only valid if, you have actually play tested and balanced the game out to actually be fun solo. If you added it and it wasn't that great it could potentially hurt your sales in the long run.