Good job making something retro like this that's compatible with old systems, but I gotta say it's clunky even considering the constraints you're dealing with. I wish it could actually respond to the mouse, even though that would mean making a special version for the browser.
I think it would be nice if the action you've selected didn't automatically become deselected after you use it, so you could easily try the same action on everything in a room. If there are 4 things in a room, I wanna select an action 6 times instead of 24 times. It would also be nice if the things you couldn't do in the demo were left out instead of left in as red herrings. There are two phone numbers in the game and a player could spend a long time trying to get the phone to work thinking the problem is just that they don't understand the interface correctly.
The item system is the most unintuitive I've ever seen, comparable to some of those games AVGN plays where the interface makes no sense. On the one hand, it's cool that you can only use items in certain places because that stops players from thinking they need to try every item on everything. On the other hand, it seems very redundant to have to walk to the exact right spot and face the right way before I can even take an item out of my inventory, and then still have to use the item on the right spot in the game world. Surely it should just be one or the other: either require the player to stand in the right spot before using an item, or let them stand anywhere and then pick the spot to use the item afterwards. Such a strange item system definitely needs a tutorial because when the pizza guy made me fish the slice of pizza out of the trash and then he kept acting like I hadn't done it yet, I thought I was going crazy or the game was just broken. It takes a while before you find a spot you can actually use an item on successfully and that moment should definitely come sooner. I still think the item system might actually be broken because I couldn't take the blue key from my inventory no matter how close I stood to the blue door or which direction I was facing, but then I remembered that I could use an item at the well so I walked back over to the well in order to use the blue key on the door on the other side of the screen!
Other bugs: I was able to walk up the wall off of the ground in the sewer. The robot is on a graphic layer in front of the player instead of behind, so that's a graphical glitch. After beating the game and starting over, there was a strange grid of numbers on top of my car and then after opening and closing a menu I was warped back to the final room.