Lot's of people are saying go mobile, but I'm not sure if that will have the precision that's currently required. Either way was it's a pretty nice game. My highscore was 639.
In the description you mention that Hank is trying to disprove the lie that the Earth is round. I don't see how that fits with the theme that the game is a liar. Though, I'm glad you didn't hurt the user experience just to fit in with the theme. One thing I was wondering is, what happens when you reach the bottom/other side or is the game endless?
Let's continue with the gameplay. The smooth transition from the menu into the game and that you shoot the menu buttons, were nice touches. The slow motion when you shoot at the enemies was also cool. However, the collecting of coins served no purpose. Perhaps you can add a store with upgrades. I also found the game to be pretty difficult in some ways, but too easy in others. For example the gravity is pretty high, so you quickly fall down. This also means it's quite hard to pick up a new weapon from the crates. I also had some difficulty with moving left and right with the gun (maybe just have A & D). Resulting in me often dying from the obstacles. However, the enemies take a very long time before they start shooting at you.
Now onto graphics and sound. Something felt off to me about the graphics, but I guess that isn't very helpful. Perhaps it's the use of solid colours. If I'm not mistaken, South Park and Kurzgesagt both use solid colours. However, Kurzgesagt looks great, while South Park looks like ... eh ... South Park. The world also feels flat. Yeah it's a 2D game, but there is no depth. It doesn't feel like Hank is falling through a tunnel; it feels like he falling in front of a green screen. Lastly the sound stuff. The sound balance was good and the sfx were alright; no high pitch coin pick up sounds ;-). Perhaps you can improve the music, but I don't know much about music.
Overall pretty nice, but some missed opportunities (like with the coins).