Click the green icon with a stick and pillow case. A.K.A. a Flag. Then, W.(Forward) A.(Left) S.(Backward) D.(Right) to move. Click to shoot, and R to reload.
Thanks to @-Cinematic- for the original project "Outbreak: In SpaceLand". I had an original project, but I couldn't get the glitches to spawn in. Tell me if you want to see the original in the comments.