On the topic of Velocity.

Is there a way to set the Velocity of a Platform or Psychics Sprite? Or should I just repeatedly change the X and Y?

Oh wow, that was the 3,000th thread in this section

Yes, when choosing a new action, at the the top of the window listing the possible actions, there are tabs to choose actions related to behaviors applied to the object

Really... because when I checked the Physics tab, it was empty. Strange, I'll doublecheck.

It's there.

For one of your conditions, click "New action." Choose the object you have the Physics behavior applied to. Go to the Physics tab. At the bottom, there should be a Velocity section with an option that says "Set velocity." It will ask you to input the X and Y components of velocity for the object.

You can also read the object's velocity instead of setting it. If you want something to happen when the velocity in the x direction reaches a certain level, for example, you could do the following:

Insert event --> System --> Compare --> select the "Value 1" field --> select the object from the list of objects at the bottom of the window --> go to the Physics tab --> choose "Get velocity x component"

You can then choose the value to compare the x velocity to. When you're done, you'll have a new condition on the event sheet. You can then add actions to that condition which will execute when the condition is met.