I didn't see the system I want, what can I do?
You can try these different solutions.
Use other keywords
Check that it is not still present in the list, by using other keywords in the search engine.
Check that it is not under development
Sources about systems under development exist:
Some developers inform the Community of their projects / progress by creating a page on the System Builder part of the Forum for their system.
Some developers inform the Community of their projects / progress by listing their system on the wiki Systems list 🇬🇧 and also possibly the wiki Systems list 🇫🇷 .
Some developers announce their projects / progress on the Discord where a moderator may have pinned their post.
Use the various search engines in these media to find the system you want.
Use the generic Let's Role! system
You can find it here: Let's Role's generic system
Use a cousin system
Alternatively, you could use a cousin system and "run with it".
For example, you could try playing RuneQuest with a system developed for Call of Cthulhu.
Fork a cousin system and adapt it
You could fork this cousin system. Go to the page of this system and click on the Other tab then on the Fork this System button. Open this new system in the System Builder and get to work, possibly with help from the Community.
Ask the Community to create this new system
You could ask the Community to create / collaborate on the development of your dream system. The Discord and (to a lesser extent) the Forum of Let's Role! are the best places to do this.