# Objective
On some platforms (observed on Windows and Linux, works fine on web),
velocity of all entities would be initialized to zero, making them
simply fall into the star.
## Solution
Using `Time<Fixed>::timestep` instead of `Time::delta_seconds` to
initialize velocity. Since the entities are generated in the startup
schedule, no time has elapsed yet and `Time::delta_seconds` would return
zero on some platforms. `Time<Fixed>::timestep` will always return the
expected time step of `FixedUpdate` schedule.
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