Description for demo by Lauri Paimen. See also the submission and commented source.
Boid simulator
Boid simulator simulates flocking behavior of bird-like objects.
Add boid with space, obstacle with enter, control behavior with B-Q keys and use your mouse to place obstacles and steer the boids.
For more information, check http://en.wikipedia.org/wiki/Boids
Controls for values affecting behavior:
B/C Grass height
D/E Maximum velocity of boid
F/G Minimum distance between boids
H/I Flock "gravity", how tightly boids flock (bigger value less)
J/K Mouse "gravity", how much mouse pointer attracts boids (bigger less)
L/M Obstacle size
N/O Perching time
P/Q Boid line of sight