I played this game years ago on Dreamcast and on that system it was a good shmup. As far as DC shmups go quality-wise it sits nicely in the middle between, say, Trizeal (good game but low-budget effort) and Ikaruga or Under Defeat.
I am mentioning Under Defeat as that game (why is it not on Steam, by the way?!) has a similar mechanic as Zero Gunner 2, where you can rotate your helicopter to shoot in different directions.

Now for the port. It's ok.
When I first booted it, the controls were way too sensitive but this was down to my screen running at 240hz. This is by far not the first game that expects a screen to run at 60hz; if we change that appropriately, the speed issues are gone and it runs fine.

My bigger problem is with the sound because I don't know what happened here but sound quality is very low. Checking YouTube I can tell the Switch version (on which this port is based) has the same low quality sound.

Overall I can still recommend the game as it plays just fine (if you set your screen to 60hz), despite the poor quality audio.

I played this game years ago on Dreamcast and on that system it was a good shmup. As far as DC shmups go quality-wise it sits nicely in the middle between, say, Trizeal (good game but low-budget effort) and Ikaruga or Under Defeat. I am mentioning Under Defeat as that game (why is it not on Steam, by the way?!) has a similar mechanic as Zero Gunner 2, where you can rotate your helicopter to shoot in different directions. Now for the port. It's ok. When I first booted it, the controls were way too sensitive but this was down to my screen running at 240hz. This is by far not the first game that expects a screen to run at 60hz; if we change that appropriately, the speed issues are gone and it runs fine. My bigger problem is with the sound because I don't know what happened here but sound quality is very low. Checking YouTube I can tell the Switch version (on which this port is based) has the same low quality sound. Overall I can still recommend the game as it plays just fine (if you set your screen to 60hz), despite the poor quality audio.