These games openly welcome third party mods. They may offer event hooks or other facilities, or maybe even have a first-party mod manager that helps you enable and disable them.
- Europa Universalis 4
- A lot of this is also true of other Paradox games eg Cities: Skylines and Surviving Mars.
- Lots of crucial numbers are defined in a Lua file and can easily be seen or changed.
- Building attributes, idea costs, country and region data, etc, are all defined by simple text files that anyone can edit.
- The Wiki has information even to the extent of creating new buildings and having them available in the GUI.
- Some behaviours (eg the AI's choices on where to build forts) are too complicated to put into those files, but this fact is at least acknowledged.
- If you edit any of these files, you get a simple cautionary note saying that achievements are disabled (perfectly reasonable), and then you're fully allowed to play with whatever balance-breaking changes you like.
- Third-party mods can be found on the Steam Workshop and the game has a preloader that lets you enable and disable them.
- Counter-Strike: Global Offensive
- Also true of other Source games eg Team Fortress 2
- This is a fundamentally multiplayer game, so the concept of game balance is extremely important. And yet Valve permit all manner of modding, either by running a custom server or by creating a custom map (or both). A lot of the power of custom servers is best made available via SourceMod and MetaMod, which are third party modding tools, but they are so highly respected that they can be considered part of the ecosystem.
- The core game includes a number of tools aimed exclusively at those trying to interact with the game, such as Game State Integration, external config files, and a parseable demo replay format.
- Factorio
- Lua, Lua, Lua! Everything's done with Lua scripts. You can tweak anything you like.
- Want to put a nuclear waste into a rocket and launch it? You can do that. And you can write an event that will fire when that happens.
- You can download the demo and play with the Lua files right there. No need to get a special custom content creation tool or anything - all you need is a text editor.
- Entrepreneur
- Lots of the key data comes from easily edited files. It's easy to mess with anything you like, although some things seem to be tied to the UI fairly closely.
- The format of those files is rigid and fragile, but fortunately they are well-commented and you can easily just tweak things within the existing framework.
- Galactic Civilisations (series)
- SO VERY moddable! You can mess around with basically everything.
- Most of the edit files are XML, which means you probably want to get a tool to edit them with, but that's easy enough.
While not specifically welcoming modders, these games do at least permit it. They might simply ignore what you're doing, with no documentation or assistance in figuring out what anything means.
- Satisfactory
- Yes, I'm putting this down here rather than in "Welcoming", even though there IS some documentation on how to mod the game. The game itself doesn't really support modding - you have to basically hack it in. I'm hoping that, by the time the game's out of Early Access, there'll be enough tools that it can be promoted to the top category.
- Making any sort of mod requires that you get the Coffee Stain Studios' modded version of the Unreal engine. And even though UE4 supports multiple platforms (kinda - it's pretty obvious that Epic don't put any effort into supporting Linux), the CSS patches don't work outside of Windows.
- The game desperately needs the equivalent of SourceMod/MetaMod (see CS:GO). If there could be such a mod, and the ecosystem embraced it, then that mod could become the one and only thing that requires UE4, and every other mod is just text files that configure the metamod.
- The devs DO notionally support modding. It just doesn't seem to be a high priority at the moment (which is unsurprising - they have a game to build, after all).
- Borderlands (1, 2, and Pre-Sequel)
- There's basically no modding support. You can edit save files but even that isn't easy. The general feeling I get from the save file format is that it came about organically as a simple dump in the most convenient way for the game devs.
- If you DO edit your save files, they load up just fine. You can even edit saves in multiplayer and it's fine with that. It probably doesn't much care what you do.
- Anno 1602
- You can mess around a lot with the built-in scenario editor, but to change the island definitions, you need an external program. You can do a lot, but be careful, as you can crash the game. It doesn't really support modding, but it doesn't object to it either.
Some games are openly hostile towards modding. All you can do is edit your save files and hope for the best. The vanilla experience is the only one the devs have considered. Attempting to modify the game may see you branded as a cheater (or worse), even if you're trying to run your own modded game among friends.
- Command & Conquer: Renegade
- Like Borderlands above, there's no support for any modding, and the game isn't easy to even read the save files of, much less modify them. The multiplayer form of the game feels tacked on, and doesn't adequately keep itself alive with bots, so since there's no strong community support for modding, the game was probably doomed from release to having a limited life.
- It's VERY easy, when editing save files, to do weird things that can crash the game. There's no info on what you can and can't do.
- Overwatch
- As an esport-level game, it's going to survive fairly well. But it will die if its owners stop developing it. There's no way for the community to keep it alive.
- Valorant
- Same as Overwatch. By not permitting custom maps, much less server-side modding, these games limit themselves to being nothing more than their creators design them to be. In contrast, TF2 and CS:GO have become more than Valve could ever have imagined.