Some suggestions/requests from a player perspective:
*Better Multibuy options, something like 10, 25, 100, max.
*A popular script addition was the ability to hide purchased upgrades and/or move them to the end of the stack.
*Draw FPS settings. I don't know about other people, but I wrote myself a little override during beta to allow me to skip draw updates. I usually lowered to 1 in 5 or 6 loops actually calling draw and saved about 1/2 to 2/3 on cpu usage. Would be nice to have a built in option to allow for slower refresh since fast HTML/CSS redraw can be somewhat cpu expensive.
*An option for forced scientific notation, limiting total digits to 3 or 4 always. Most new games today have a similar option.
*Option for things to show actual production w/ multipliers, not just base. I'm not sure why a player would want base at all, so forcing it to show actual would be fine with me.
*Constraint for random object spawn. In the bunny demo, for example, the bouncing rabbit frequently jumps off the top of the screen. This might not really be feasible depending on what you let authors do.
*Confirmation for wiping your game. Again another super common beta script people used. It's pretty silly not to have it.
*Option to Export/Import using clipboard. If it is going to be large, like string.length > 500,000, force save to file, maybe?