Pixel Game Maker Series STEOS -Sorrow song of Bounty hunter-

This game looks like a side-scrolling shooting game at first glance, but the main character is not a fighter, but a bipedal cannon. It's a high-difficulty action game with a screen doesn't even scroll. The distant future when AI has taken over civilization. Suddenly AI divided into Migma and Apeiron armies and started war. You are a human hired by the Migma army with the expectation that you are indeterminate element that will bring victory. With only two weapons - a only horizontally and at 45 degrees bullet, and a spanking bullet that a very narrow range - you board the bipedal cannon Steos and embark on a fierce battlefield of AI.