Time
You can use time() to get the time the program has been running in seconds,
and delta_time() to get the time since last frame in seconds.
There is also physics_time() and physics_delta_time() which uses the
‘physics timer’. The physics timer can be sped up, slowed down, and paused using
set_physics_speed, pause_physics_timer and play_physics_timer. This
isn’t related to the physics system, and wont speed it up.
There are also some convenience methods you can use, like once_per_second or
once_per_n_seconds which only returns true once every some timeframe, and
oscillate which moves between two values once per second, oscillate_t lets
you provide your own time value, so you can speed it up or whatever.
See: time module for full list of functions