Easy Trajectory is a simple script that predicts the necessary speed and direction necessary for a projectile to be lobbed towards a pair of target coordinates. The sample file contains everything necessary to get things working. Left-cick anywhere on the screen to lob a grenade towards the mouse coordinates!
It is as simple as calling: GetTrajectory(target.x, target.y);
Makes use of particle trail scripts found here: https://marketplace.yoyogames.com/assets/212/draw-trail