u/Fevrall

Platform: PC, either flash or downloadable (possibly freeware or shareware)

Genre: 2D action sidescroller

Estimated year of release: Early-to-mid 2000s (roughly 2001–2006)

Graphics/art style: Vector art (smooth, Flash/GameMaker-style), almost entirely grayscale, the player character, enemies, and environment were nearly all shades of gray

Notable characters: You play as a humanoid, knight-like mech, slim and armored, resembling a suit of sci-fi plate armor rather than a bulky war machine

Notable gameplay mechanics:

• You can freely float/hover on both X and Y axes - no gravity, full 2D movement through the stage
• Some attacks are triggered by Street Fighter-style directional inputs (quarter-circle motions + attack)

Other details:

• The game is set inside a spaceship or space station (at least the first level), corridors with a sci-fi interior feel
• You exclusively fight robots and machines, no organic enemies at all that I remember
• The game has boss fights
• The overall palette and aesthetic was very monochromatic lots of gray tones

Been searching for it on and off for a few good years, hope someone can set me free!