The best shooter games like Gunstar Heroes are Alien Soldier, Contra III: The Alien Wars and Metal Slug 3. Below are 10, each with the reason it is here — and, at the end, what filtering to shooter costs you.
Filtering to shooter means you want the guns to be the answer. It is the right filter when what you liked was the feedback — the sound, the recoil, the way enemies react.
What you get: Moment-to-moment feel, and the shortest distance between picking a game up and enjoying it.
What made Gunstar Heroes worth playing in the first place is covered on the full list. This page is the shooter part of that answer, and only the shooter part.
Treasure again, harder and faster, and the boss design is relentless.
The other peak of the genre, and the better-balanced of the two.
The most generous run-and-gun ever made, and superb in co-op.
Made specifically to be this era again, and it succeeds.
A polished modern arcade run-and-gun with great co-op.
Boss-pattern run-and-gun with the same density of invention.
Destructible run-and-gun chaos, four players, very funny.
Treasure's shooter, and the design people still study.
Treasure in three dimensions, aiming and moving as separate jobs.
A modern shooter made by people who studied Treasure closely.
Variety. Shooters commit hard to one loop, and the ones that try to be something else usually do the something else badly.
Specifically, these are strong answers for Gunstar Heroes that are not shooter games, so they are not on this page:
The full list is on games like Gunstar Heroes — 12 picks, no genre filter.
Alien Soldier. Treasure again, harder and faster, and the boss design is relentless.
No. Gunstar Heroes released on the Sega Genesis, but a recommendation is only useful if you can play it, so the picks above span platforms and eras. What they share is the genre and the reason.
How the guns sound and how enemies react to being hit. A shooter with mediocre levels and superb weapon feedback is more fun than the reverse, every time.
Each pick says. Several of the best shooters ever made are single-player campaigns, and a few of the co-op ones are genuinely worse with bots.
By hand. Each pick was written for the full Gunstar Heroes list first, on what the game actually does, and this page is the part of that list that is shooter — never a genre tag lookup, which is how "best racing games like Super Mario 64" used to be a page on this site.
Or read the shooter guide for where to start in the genre generally.