This is a weird multidirectional shooter with time portals that allow you to travel between eras and rescue lost soldiers. Weirdly, the game allows you to travel to the wrong era, and then you have to find another portal to go to the correct era. Heartbreakingly, I was using the built-in autofire to brute force my way through the game, but on the final level I held it down after dying, entered a hiscore, and skipped the continue countdown without realizing, and it was a game over.
Screenshots marked with 🍒 are created by syltefar and are considered public domain, free to use for anything. If you want to, you can note where you found it and link to this page.