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Navigating LGPL 2.1: Why I Chose Not to Use Open-Source Playing Cards in My Klondike Solitaire Game (And How You Can)

I started to develop a Klondike solitaire game and initially I explored using a set of LGPL 2.1-licensed playing cards in SVG format. It seemed like a great option at first—after all, the graphics were high-quality and freely available under an open-source license. But as I dug deeper into the requirements and technical considerations, I realized it wasn’t as straightforward as I’d hoped. Here’s what I learned and why I ultimately decided not to go that route.

1. Keeping the Playing Cards Separate

The first challenge I encountered was the requirement that LGPL 2.1-licensed assets, like these SVG playing cards, need to be kept separate from the core game code. This is so users can easily swap or modify the cards if they choose. For my game, that meant I couldn’t simply integrate the cards directly into the compiled code. I would have had to serve them as external assets that load dynamically, which, while possible, added a layer of complexity I hadn’t initially planned for.

2. Providing Access to the SVG Files

I also learned that, under LGPL 2.1, I needed to ensure users could access the original SVG files. This requirement applies whether the game is played in a browser or downloaded as software. In practice, I would have had to either make the SVGs downloadable from my website or ensure they were accessible in the game’s asset folder. For a web-based game, this meant making sure they weren’t bundled or hidden in the game files, something that could complicate the way I structured my game’s assets.

3. Including the LGPL 2.1 License

Another key requirement was providing a copy of the LGPL 2.1 license and attributing the original creators of the playing card graphics. While this seemed simple at first, I realized it wasn’t just about adding the license to the game’s credits page. I also needed to ensure the license was included with any distribution of the game, whether online or as a downloadable file, which added another layer of work to make sure all bases were covered.

4. Allowing for Modification

The LGPL 2.1 requires that users be able to modify the licensed assets, and I had to make sure my game supported this. Although I didn’t need to provide users with editing tools, I had to ensure they could load alternate card designs or modify the SVGs in their own way. For an online game, this would mean structuring the game to dynamically load the card assets, which introduced more technical complexity than I was comfortable with, given my timeline and resources.

5. Distributing Modified SVGs

At one point, I considered tweaking the card designs to better fit the theme of my solitaire game. However, I soon realized that if I modified the original cards, I would have to distribute those modified versions under the LGPL 2.1 license. This wasn’t a dealbreaker, but it did mean I’d have to ensure any changes I made were freely available to others under the same license. Managing these modified assets, along with the need to attribute and distribute them properly, felt like additional overhead I wasn’t keen on taking on.

6. No Restrictions on SVG Files

One important aspect of the LGPL is that I couldn’t impose any restrictions on the SVG playing cards beyond what the license already allowed. This meant that, even though my game was commercial, I couldn’t lock the cards behind a paywall or impose any conditions that would limit user access. The playing cards had to remain as open and accessible as the license intended, which didn’t quite align with some of the commercial aspects of my project.

7. Dynamic Use of the Cards in the Game

Finally, the LGPL allows for dynamic linking, which means the playing cards can be used in the game without being embedded into the core code. However, this also meant I’d need to set up my game to load the cards dynamically rather than baking them into the game itself. While technically feasible, it introduced more complexity than I anticipated and didn’t fit well with my existing development approach.


Why I Ultimately Decided Not to Use LGPL 2.1-Licensed Cards

After working through all these considerations, I realized that using LGPL 2.1-licensed playing cards wasn’t the right fit for my Klondike solitaire game. The technical overhead of keeping the cards separate, ensuring dynamic loading, and maintaining access and attribution compliance just added too much complexity to my project. I was looking for a solution that would streamline the development process, but these requirements ended up complicating things far more than I expected.

In the end, I decided to go with a different set of assets that didn’t come with these restrictions, which allowed me to focus on building the game itself rather than navigating licensing and technical hurdles. While LGPL-licensed assets are a great option for some projects, in my case, it just didn’t align with what I needed.

Alternatives

Luckily, there are many alternative less restrictive and a few are in public domain:


Using LGPL 2.1-Licensed Assets: What to Consider

Using LGPL 2.1-licensed assets, like the playing card SVGs, can be a great option, especially if you’re working with open-source resources. However, the license comes with certain requirements:

  • Separate the Licensed Assets: The playing cards must be kept separate from the game’s core code, ensuring they can be modified or replaced by users.
  • Provide Access and Attribution: Users must have access to the original files, and the LGPL 2.1 license must be included along with proper attribution to the creators.
  • Allow for Modifications: Users must be able to modify the assets and use their own versions in the game.
  • Distribute Modified Versions Properly: If you modify the assets, the updated versions must also be distributed under the same LGPL 2.1 license.

If your project can handle these requirements, LGPL 2.1-licensed assets can be a powerful and flexible solution. In fact, I worked out a compliance strategy during my development process, but in the end, I decided it wasn’t the best fit for my game due to the added technical complexity. Still, here’s the strategy I developed to comply with the license before I made that final decision.

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