Fix: Some more refining, and OpenGFX2 message.

Author: michicc

_posts/2025-12-07-openttd-15-0-rc1.md

@@ -8,11 +8,13 @@ Good things come to those who wait. OpenTTD 15 is starting the final lap with fi
 With a release candidate, the focus shifts from adding new features to finding and fixing bugs to make OpenTTD 15 the best OpenTTD yet.
 The finding part is where you, the players, come in, too. If there's anything you notice, head over to our [issue tracker](https://github.com/OpenTTD/OpenTTD/issues/new/choose) and make a report.
 
+If you've already played any of the betas and use the OpenGFX baseset, you might have noticed a message about missing sprites. This is due to some of the new features in OpenTTD 15. We recommend switching to the newer (and still updated) OpenGFX2 baseset, which you can easly get via the in-game content downloader.
+
 Some notable changes over the previous beta3 release are:
 * Automatic font loading for characters not part of the normal language files (like e.g. player names or chat messages)
-* Terrain generator can make wetlands for rivers unable to reach the sea
 * Signs, waypoint and station names may be moved
-* Draw infinite water when all borders are water
+* Terrain generator can make wetlands for rivers unable to reach the sea
+* Island maps and heightmaps can be surrounded by infinite water instead of black
 * Bridges can now be built over locks and docks, too
 * Various tweaks to interface scaling
 * Improvements and fixes to badge support