by feel right i meana:

consistency (you want all your assets to work well together)

practicality (important things like the player, collectibles, power up's, enemy bullets should all pop out of the rest of the game, don't wanna make the background art so detailed it's the only thing your brain can process 🥔)

and finally, color theory (not only do you want all your colors to feel right, but you also want a warm place to feel warm and a cold place to feel cold and so on)

i see so many indie devs making games with the idea that all they need to learn is how to code, witch is just wrong

if you actually want your games to succeed then you'll need to learn things like sound design, marketing, graphic design, story writing, scene composition and a lot more, so you better get ready for all of that 🥔

or you could just make a short horror game and then plead for someone slightly popular to play it, that works too 🥔

(all of that also applies to people who are working on big undertale fan games)