The Line Attractor node seems to render differently (have different strengths) between Cascade Viewport, Editor Level Viewport, PIE and Standalone/Launched Game
In trying to capture movies for this JIRA, I also noticed that when FRAPS is running and the Framerate drops from 120 to 90, the Particles render as they do in a launched game and Cascade.
The particles also render correctly in the Editor Viewport if Cascade is open and visible (on a second monitor or otherwise)
Also Reproduced in Main-CL-2660934
New Repro
RESULTS
The Strength of the line attractor module appears to change with the frame rate.
EXPECTED
The Strength remains consistent despite variance in frame rate.
Old Repro
RESULTS: The Editor is not correctly previewing the particle system in Editor Viewport
EXPECTED: The particle system should always render the same.
Head over to the existing Questions & Answers thread and let us know what's up.