The best shooter games like Just Cause 4 are Just Cause 3, Saints Row IV and Crackdown. Below are 5, 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 Just Cause 4 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.
The tighter of the two, and the wingsuit is unchanged.
Superpowered traversal in an open city with the same silliness.
Traversal-first open world where movement is the upgrade.
Open-world chaos with a grapple and a wingsuit of its own.
The other great blow-everything-up sandbox.
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 Just Cause 4 that are not shooter games, so they are not on this page:
The full list is on games like Just Cause 4 — 9 picks, no genre filter.
Just Cause 3. The tighter of the two, and the wingsuit is unchanged.
No. Just Cause 4 released on the PC & Modern Multi-Platform, 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 Just Cause 4 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.