dude, Definitely 1 of my NGFAVES-and i got ideas!!
first of all i just wanna say the combination of the crazy colors, overall trippiness (like the beuatifully drawn mushroom) and the amazing music make this an Easy 10/10. i love how such a simple concept can be so addictive to play it again and again, much better than the first. amazing what a cool color change can do.
And also as a wannabe future game designer, i had some cool ideas for the yellow pill. if ur lookin for something easy, you could turn into one of the other cool fish you drew in this game, maybe change the colors up and have all the other fish and birds go in a slight slo-mo while you are able to jump really high out of the water to catch even the highest birds.
A harder idea i thought of is when u get the yellow pill, the gravity shifts upside down, (only for the player controlled fish), but after flying upwards for a few seconds you splash into another body of water coming from the top of the screen and the controls would remain the same. only exception is that in this water there are only jellyfish, or some other harmless type of "bonus fish" say sea stars for an example. and than after about 20 or so seconds you would fall back down into the regular ocean where big fish are again a threat. Now i have no idea how hard any of these ideas are to produce since i dont reallly make games but more of "interactive moveis" so i dont wanna sound crazy. but i got one last idea.
if you got the yellow pill, maybe you could have a large lit up aura around you that would allow you to see the "deep sea fish" that you cant see when you go in the dark area normally. and the bars with arrows on the side drain the whole time to show how much light u have left. and the yellow pills would be scattered underwater in order to keep the light on as long as you can maintain it. haha maybe you could even make a sea floor with edible sea weeds for extra points and little crabs with claws on the bottom to try and grab you. who knows man im just throwin ideas out at ya.
But seriously if you do use one of these ideas or ur thinkin about it, or even if u like these ideas, PM me man. I'd be honored to see u actually use one of em and theres more ideas where from those came from. haha so yeah good luck with ur yellow pill and once again.. Amazing game