Based on a manga/anime series.
Game Boy Advance (2003, published in Northa America and Japan by Sega, in Europe by THQ) Treasure assisted somewhere in the development as well.
1 player
https://www.gamefaqs.com/gba/918953-astro-boy-omega-factor/faqs/41734 (The game also has a tutorial mode if you choose, so you really don't need me to lay out a move list either way)
This one can get a bit complex, as it blurs genre lines. You need Astro Boy to meet new characters so he can unlock(or more realistically, power-up) his abilities. You can meet some characters and still not be able to use the power-up you should, until you've been through the game a few times, finding them again each time, until Astro finally understands them. So you have to search for characters created by Osamu Tezuka, which runs the gamut of his manga/anime creations(so yeah, crossovers in a lot of cases).
Items, mainly hearts, for health, are picked up by walking over them. Enemies can come in various sizes, though unfortunately get more pixelated(blocky) the larger they get. Bosses have meters, so you know how well you're doing during boss battles(you're most likely better off building up the Ex meter during stages so you can use the Ex moves fairly freely against the bosses). Some segments of the game play like a shoot 'em up. Though you can punch and kick, it may be easier to rely on ranged weapons.
I'm not exactly sure how saving works, but I think the game autosaves when you reach a new location.
Fun fact: Osamu Tezuka pretty much created anime with Astro Boy, which in turn was inspired by Carl Barks' creation of Scrooge McDuck. Essentially anime might not have come about if not for a character many didn't even know existed until DuckTales.