There are some xpm/xbm tiles included in the current (2.5.2) CDE source code on https://sourceforge.net/projects/cdesktopenv/. The NsCDE list is nice!

I think if it’s based on a time period or location that you’re all familiar with, it will definitely help everyone become immersed. If you’re the DM/GM/referee, I think the more familiar you are with a setting the more you can help get your players immersed even if their familiarity is somewhat less than yours. This has been my experience as both referee and player.

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This worked for me for a couple of communities that were stuck in the ‘pending’ state.

There’s a lot of extra but it’s not necessarily filler. It would all depend on whether you were going to run your game in the Aventuria world and/or wanted the Theater Knights campaign. It depends on how much of the published stuff you want to run.