Your game is cute!
I like the INSTANT directions you give to players on how to play and get into the main action (IT’S VERY IMPORTANT!).
The graphics are cute and simple.
The main action concept could be stronger though. I have my theory of what mainly makes a game fun, and, in my opinion, your game’s main mechanics need improvement.
The theory is that a game is fun when it encourages you to think (figuring out how to achieve some task), or at least gives an illusion of thinking through stuff.
Another problem is the attention span of most players I think is very short - you got about 30 seconds to catch attention and catch it WELL.
So I RAN through the tunnels for a few minutes and didn’t need to think much (yes, a simplified concept is very good, but there is this thing as being “too easy”).
It’s very simple to avoid obstacles and when i fell, I didn’t lose progress, so it became even more easy, not challenging enough. As I mentioned before, most players play for a few minutes. In those critical seconds/minutes, they get the first stages/levels, and in them, there’s not much to think about. In my opinion, players can quickly lose attention and jump into another game in an instant.
And I think I noticed a minor bug right at the beginning?
The popup dialog at the beginning failed to disappear, also with the accompanying button “run”, letting me spam teleport to the lobby. It’s a minor issue, it disappeared when I entered the first portal, all good.
Tried to upload a video here to show it to you, but apparently, 9 seconds is too much for Roblox 
And another minor issue I encountered is the first time I loaded your game, it told me to click, I did… nothing happened. I would recommend making it easier to get into the game by letting click anywhere on the screen, not only the dialog at the bottom, but it’s not necessary, you got a nice finger pointer showing where to click, but you know… at first join not thinking much, the aforementioned short attention span… 