First things first. Two of the most simple and commonly used items are “Sprites” and “Objects”. Simply put, a “sprite” is basically just an image, and an “object” is the physical being that goes into your game that can be controlled to move, jump, etc. In other words, typically, you will create a sprite by loading an image (image 1) and then load that sprite into your object (image 2). That gives you a physical object that you can now add to your game room and control. Furthermore, you can have more than one “instance” of your object in a game. You can think of an “instance” as a sort of copy of your object, and each instance of an object acts the same within the room. One other common item is a “sound”, which is exactly how it sounds (no pun intendedJ). But seriously, you can load an .mp3 or .wav file into a sound and have it play at some point in your game.
Now, how to control your object? For controlling an object, there’s two things you need to know about, “Events” and “Actions”. Typically, the way it works is, you tell your object what event to listen for and how to respond to that event. In other words, an event is basically a trigger, and when triggered, it executes its assigned actions. For example, if you use the create event with a move action, you are basically saying, “When my objects is created, I want it to start moving” (image 3). Other common examples could be “When my object collides with another object, I want my object to bounce back” or “When the user clicks on my object, I want to play a certain sound”. Don’t worry too too much about the specifics of this yet, but do make sure you understand how events and actions are connected and used. The concept is simple, but can take you a long way in making games and even in programming.
The last two items that I will mention are “rooms” and “backgrounds”. A room is simply the place in which a game is played. When you create a room, you can add, for example, an object and a background. That said, a background, similar to a sprite, is basically an image of some sort and is used as the backdrop for a room. So if you create a room and give it a blue background and add a turtle object, you will –as you might expect- see a turtle standing in front of a blue backdrop.
In summary, sprites are basically images that are used to create objects, which are controlled by events and actions. Furthermore those objects along with a background can give your room some substance. As I said earlier, this is not a tutorial, but more an introduction to the most basic concepts in using Gamemaker. I hope this helps, and check back in a few days, as I will have posts covering movement, creating start and end screens, and more! Please comment with any questions or suggestions.