Modding games that have already been made is a GREAT way to practice gamedev skills! Especially art and level design. For this I would recommend SLADE or other DOOM modding programs. SLADE allows you to explore the original game's WAD files, export assets to modify, import new assets you've made, and create entirely new mods to run on programs such as GZDOOM. Many modern games, including SELACO and HEDON were made using a modified DOOM engine.

I like to suggest DOOM over 3D games as modding games such as Half-Life and DOOM 3, once an easy task with great tools and tutorials, has been left far behind in the dust and learning to mod these games is much more difficult now than it was in their heyday. Though, not impossible if it's something you'd like to try. While the "in-between" of QUAKE map modding is still alive and well for classic 3D level designs!

Adventure Game Studio is a program designed to make building point and click adventure games similar to those made by Sierra Entertainment and Lucasarts in the 90's. Many modern adventure games such as KATHY RAIN, and games made by WADGET EYE (Unavowed/ Primordia) were made in AGS. Although, possibly a little more complicated than other game development suites, the fact that AGS is designed to make a specific type of game means that, once you've mastered the workflow of a project, making a new game is as simple as swapping out assets such as art and dialogue. But the program isn't as limited as you might think as the side scroller UNTIL I HAVE YOU was also made in AGS and is NOT an adventure game! So there is much flexibility here if you want to make it work.

There's a lot to say about PICO-8, but the first two are; it's not free ($14.99 USD) and due to the tiny resolution (128x128 for game and dev environment) it can feel VERY cramped to use. However, PICO-8 is amazing as it's a complete gamedev package that's all self-contained in one program. You can write the code using the LUA programming language, make a sprite sheet, make music, and make sound effects all in one place then upload that game as a "cart" to an internal database that other users can browse and play! It's not really meant to be a commercial release platform, but more of a fun prototyping system as it has many limitations, but if you want to practice 2D gamedev there's no "all in one" package like PICO-8! You may even have heard of a little game that came out on PICO-8 back in 2015 as a gamejam entry called CELESTE.

LÖVE2D or "LOVE2D" is my preferred 2D programming suite. Unlike all the previously listed gamedev programs this one isn't a kit, but an engine that you run your data files through to make a game happen. I enjoy LOVE2D because it shares the same programming language as PICO-8: LUA and has very simple requirements for making a game run while maintaining a lot of flexibility. I write my code in a notepad program, make my art in an art program, put it all in one place, then run that code through LOVE2D which outputs a game in its player window. I would consider LOVE2D to be an "intermediate" skill gamedev route as nothing is laid out for you. There are many tutorials, guides, and a helpful community, but it's up to you to make the art, write the code, tie them together, then make them work in LOVE2D. This is both very easy and can be very frustrating as there is no hand holding or specific paths you must take to make a game with it. In fact, even though LOVE2D is a 2D game engine I was able to convert some raycasting code to LUA to make a Wolfenstein3D clone. My current commercial game ANDY BLAST VS THE FORCES OF EVIL is made using LOVE2D.

It has been many, many years since I have touched RPG Maker, but it is still going strong. Much like Adventure Game Studio, RPG Maker is designed to make one type of game; RPGs! It contains all the tools you need to make tiled maps, characters, dialogue, combat sequences, cutscenes, etc, all in one package! When I first tried the program I didn't like how limited it was, specifically that all combat actions were first person, similar to Dragon's Quest for the NES and not side aligned like Final Fantasy. (I used to be picky about things.) However, over the years the program has become much deeper and much more flexible due to the wonderful people who have not only continued to develop it, but the vast number of users who have churned out many amazing games using it! (Which I will not be linking because of the NSFW content)

A long time ago I found a program for Windows XP(?) that let you drag and drop tiny programming icons into a grid and type in variables to make a game. It was one of the first "no programming" gamedev suites available. GAMEMAKER is not that program (I don't think), but I stumbled upon it while looking for my mysterious program for re-download. It does have the same "no programing" drag and drop interface, but has become a very powerful development suite for 2D games. I will admit I've never made anything in it as I found LOVE2D shortly thereafter and haven't looked back, but I wanted to give it an honorable mention as (potentially) being the modern version of a cute little drag and drop programing suite that I fell in love with many years ago. And, I will admit, some of the games that have come out of it have been amazing such as EXOPHOBIA and HYPER LIGHT DRIFTER.

For me, there is only one program I enjoy using for writing raw code and that is NOTEPAD++. It can run multiple tabs, customizable color themes, and a multitude of built-in language support that covers nearly every coding language. For specific language variants, such as LOVE2D's specific functions in LUA, you can install your own syntax recognition system and get spelling corrections and auto-complete options with function descriptions! Overall, there's not much I can SAY about NOTEPAD++, but that's because I barely scratch the surface of its functionality since I mostly use it for the themes. If there's one complaint I have about the program it's that there's no version or alternative like it for LINUX machines.

Many of my computer class hours were wasted making terrible drawings in MSPaint in the before times. Although MS has officially removed the program from Windows you can still find remakes of it in online browsers and for download around the internet. Although, mostly for nostalgia and with less functionality than other, modern options if you have a slow computer, no budget, or otherwise just need quick "programmer art" then something as simple as MS Paint could be the thing that saves the day for you!

Aseprite is one of the more mainstream options on this list of development tools, but with good reason; it's cheap ($19.99 USD), flexible, and powerful as a professional pixel art program, but also easily usable for beginners. It has layers, "Onion" layers for animation, reference image loading, custom color palettes (I prefer Rosey-42), still image export, gif export, internal resizing, and a slew of controls and functionality that are always being added on to. If you can't afford to pay for a copy there is a free version with less features and, if you have some ability or a good friend who can compile from source then they allow you to do that for free!

GIMP is a free Photoshop clone with many of the same features. Although not my preferred choice for making pixel art, it is very capable of doing so with the added bonus of allowing for features that traditional pixel art programs do not (such as making normal maps if you want). If I had one complaint about GIMP it would be that, much like its 3D cousin BLENDER, it tends to have a complicated "programmers" interface that takes a lot to get used to with many features hidden behind drop down menus and click through icons.

Tiled is not so much an art making program as an art assembling program. By telling it how big you want an image to be and how big the tiles of that image should be you can create a "map" that can then be filled with pre-drawn tiles from a sprite sheet. This allows you to quickly build maps and backgrounds for games using a few assets rather than drawing the entire element by hand. Tiled has the ability to do top down, front, and isometric views to incorporate into many different game designs.

SoftImage XSI (Mod Tools) was the 3D modelling program of choice for modding Half-Life and is still a powerful modeling program. Being specifically designed to mod a game that, at the time, was cutting edge, but now would fall into the "low-poly" category of game development this tool is well hidden and often overlooked. Even though this is a demo of the full SoftImage modeling suite it is still powerful enough to make and animate models. The MAJOR downside to this suite is that it is not capable of outputting models in a format that is used for modern engines. There are ways around this, but that becomes complicated. Still, as this is a list of learning tools, if you ever felt the urge to put a Minecraft-style model in Half-Life this is the way to go.

During my foray into 3D space when the options were highly expensive programs like MAYA and 3D Studio Max I came across a little program called TRUESPACE3D by Caligari. Unlike the other 3D programs it was not split into four windows of different viewing angles, but had one large window that you could spin and turn the camera around. It also had direct point manipulation which, for my style of modeling, was perfect and it was the only 3D modeling program I used and still use today!

When MS bought Caligari they made Truespace 7.6 free, but I prefer 3.1 which has a less "modern" look which doesn't slow down my computer as much and still runs on Windows 11! Although not the best program when compared to Blender, I mention it here because it has a much smaller learning curve than Blender, runs fine on modern systems, is free, and can be used to make props, models, and figures that can be textured and rigged once converted to a "modern" format (usually OBJ).

Audacity is a free audio editing suite that allows you to import, manipulate, and export audio in multiple formats. It's free and very easy to use. While it can be used to just convert a WAV to an OGG to save space in your game download you can also use it to make sound effects, alter music, rearrange tracks, anything you might want to do to a pre-recorded audio file.

Bosca Ceoil is a music making program made by Terry Cavanagh (the maker of VVVVVV and Super Hexagon) which was distributed for free and has recently been remade! Using it is a little like using a music Tracker, but all the sound files are internal. Select an instrument, place a note in a block, arrange blocks to make music. It can be a bit intimidating to use, at first, but if you have any musical inclination it becomes very easy to make some simple tunes and even more complex tracks if you want to put in the effort.

Very recently the BBC (British Broadcasting Corporation) released its ENTIRE sound effect archive online for anyone to search, download, and use. A quick search of the library shows it to be a lot of "filler" sounds such as crowds and nature, but with Audacity it would be easy to make any number of sounds from these and with over 33,000 sounds total I'm certain there's more in there than what I was able to look at in just a few minutes.

Freesound.org is a website that offers free sounds and sound effects made by its users. It can be a great source of free and open-source sounds, but not all sounds are free to use and quality can vary widely between sound makers. If you need sound effects and don't want to make your own this is the place to go. When combined with Audacity, provided the license allows you to manipulate the downloaded sounds, it can be a powerful place to load up your game with noise!

Kevin MacLeod is, to me, the "music of indie games". You can hear his free music in YouTube videos and popular games such as KERBAL SPACE PROGRAM. He has paid music, but he also maintains a "royalty free" area where, as long as you credit him, you can use his music in anything for free! As a bonus, he uploads his music to the YouTube Audio Library for use in videos so there's very little chance of having a copyright strike on any gameplay videos you may post!