what game is this?

i remember playing a game over my neighbor's house years ago (maybe 5?)

i had almost beat the game in one sitting and i thought it was a pretty cool game, i totally forgot the name or what system it was on, i was hoping someone could help me out

the main hero was this little kid with a really big head and for attacks he would bonk enemies with his big head

anyone know what game and system this was on? (sorry for the lack of info.)
That's a PC Engine/TurboGrafx-16 game called Bonk's Adventure. Bonk (known as "PC Kid" in Japan) was the system's mascot. If I'm not mistaken, he eventually made his way to NES and Game Boy as well, but the PCE ones are the best.
There's SNES versions too (BC Kid), I think the second one was only out in Japan for it though.