When scouring the internet for various things to help you with your project, make sure you are aware of any applicable copyrights and usage restrictions. You don’t want to accidentally get into legal trouble!
Most of the resources listed here are free or have free versions.
SOFTWARE AND GAME ENGINES
This game development program is one of the industry standards. It has a pretty steep learning curve, but there are a lot of bells and whistles to work with.
One of the simpler game development tools out there, you can still do quite a bit with it.
This website will let you make retro-style sound effects for your game. You can download your creations and add them to your project. Note that you will need Flash for this site to work.
COURSES, TUTORIALS, ETC.
This section will list helpful tutorials, courses, YouTube channels, etc., that can help with video game development.
I’ve been aware of gamesplusjames for a while now. His YouTube videos are great and there are a ton of them covering the creation of different kinds of games. He also has a few courses at Udemy. Most (all?) of James’ content is done through the Unity game engine.