Here are some resources for creating games. Feel free to reply with more suggestions or offers to contribute, and I'll update the list accordingly.

Note: These are just suggestions to help you out. Don't feel like you're required to use any of the following.

Sortingh.at is a great site if you want to get into game development, but have no idea where to start. It gives suggestions for game making programs, as well as other resources such as art and sound assets. I strongly recommend looking at it before you start.

Game Making Programs:

These are programs for making the actual game. Programs I've marked with "(free)" are totally free, while others cost money for the full versions (but have free versions available).

• Twine (free) - A text-based program, and a great way for beginners to start creating interactive stories and games. Simple to learn, especially with a tutorial. Note that version 1.4.2 is way easier to use than version 2.0.11, especially if you want to add pictures or anything like that. This is what I used to make Clowning Around and Sacrifice.
• Inform 7 (free) - Another text-based program, and a little more complicated and versatile than Twine. It has in-built tutorials, but I also found these ones really handy. This is what I used to make Impetum Maleficus and Endless Sands.
• GameMaker: Studio - Great for making 2D games, GM:S uses its own system that requires little to no coding knowledge to use. There are plenty of tutorials on the website. This is what I used to make Spirit Smooches.
• Unity - I have very limited experience with Unity, it seems very complicated but extremely versatile. If you want to make a 3D game, Unity is probably the way to go!
• Construct 2 - I haven't personally used Construct 2, but I gather it is similar to GameMaker: Studio in many ways.
• RPG Maker - I also haven't used RPG Maker, but it seems like a good way to make games without having to worry so much about art and sound assets (since it comes with a bunch, and more are available on the website).
• Adventure Game Studio (free) - Again, I've never used this program, but it seems like a good option for creating point-and-click adventure games. As an added bonus, it's completely free!
• Clickteam Fusion 2.5 - Once again, I've never used this one before. But I've heard good things about it!
• The Godot Engine (free) - I've never used it, but it seems to have a great toolset. It's open source too, so there are plenty of extra features, and with a little know-how you can add more.
• Superpowers (free) - Another open source program that is apparently easy to get started with, and allows your game to be played in a browser.
• Ren'Py (free) - A tool that's really useful for making visual novels, or similar types of games.
• GDevelop (free) - An open source and cross-platform program for game making, that apparently requires no programming knowledge to use.
• Bitsy Editor (free) - Very simple, but very cool!

Art Assets:

Unless otherwise noted, these assets are royalty-free. However, before using art assets in your game, make sure to check the sites for the correct way to credit the artists.

• Itch.io - There are a LOT of assets here, definitely worth a look. Some are free, some aren't.
• Open Game Art - Lots of neat art, particularly for low-graphics games.

Sound Assets:

As above, these assets are royalty-free, but most must be credited correctly.

• Free FX Samples - A zip file my Sound Design tutor gave the class, which I'm hosting on my Google Drive (just click "Download" in the top right). No need to credit, these are stock! The file types are weird, but they open in audio editing programs such as Audacity no problem.
• Incompetech - Lots of great music for various themes.
• MusicRadar  - The general site is aimed at musicians, but that link will take you to a big list of royalty-free resources. They're not all winners, but some are excellent!