Yellow Robot with Weapon — Gold

1600 × 1200

Four Soldiers in Gas Masks — Gray

1200 × 960

White Robot with Red Light — Gray, Calm, Digital Art, Red Heart

1440 × 900

Aperture Laboratories Logo — Black, Neutral

6000 × 1800

Portal in Wall — Gray

1920 × 1200

Two Anime Girls with Mecha

1680 × 1050

Mech Robots in Desert

5000 × 3596

Mech in City Street

1152 × 864

Solar Sail Boats

1600 × 1200

Silhouettes of Three Soldiers

1600 × 1200

Woman Holding Portal Gun — White, Dramatic, Digital Art, Robot

1084 × 1600

Companion Cube with Hearts — Blue, Melancholic

1920 × 1200