Where are they seeing the price? The demo is immediately below the buy button on your page from what I can see. Maybe you can put the text "demo available below" right next to the purchase button in the reward description. I'm not sure the best solution for this either. I think showing an icon or something that signifies demo on the browse pages would be helpful as well.
I don't think making a separate page for the demo would help.
If people search for "The Moon Fields" or "Local Multiplayer" they end up seeing "The Moon Fields $20". I gave one person the link https://lunarsignals.itch.io/the-moon-fields telling them that there was a demo, and they thought that the demo was $20.
I'm not really good at website design, but I think one of the problems is that the early access has kind of a big leadup with the Exclusive Content header and the outlined section for the particular First Access Key reward. The demo doesn't seem to have much parity? I don't know.
I guess the way I see it is I'm offering two products - one for free and one for $20. I made a similar game before at https://interdimensional.itch.io/combatjr, and it's consistently getting more views and downloads than the demo for The Moon Fields. The idea behind my demo here was to make it Combat Jr obsolete, and the full version was a reason why people would want to buy into The Moon Fields. E.g. people can find value in The Moon Fields as a demo but also give $20 to the development of the final full version.
I would be fine if by searching The Moon Fields people would see that the game was at the lowest price of zero, but also buy more content at $20.
