Release Notes 1.15.6
New Content
New Fauna Units
Several new fauna units have been added to the core game. These are the Tusklet, Gorer, Crocodile, Bear, Icemonax, Great Icemonax, Bear, Stoat, Giant Ant, and Fire Ant.
New Terrain Variation
The "Overgrown stone walls" terrain variation has been added to the in-game map editor.
Delay Advancements Modification
A new "Delay Advancements" modification has been added to mainline. When enabled, this changes an aspect of core gameplay - when playing an online multiplayer game, units that reach the required experience to level up on another players turn will not advance until it is your turn again. While this does mean that your opponent(s) will be able to continue attempting to kill that unit until it becomes your turn again, it also means that you will always be able to choose what the unit will level up into, rather than the current situation where a unit that levels up on another player's turn will have one of its advancements chosen at random.
Changes To Existing Content
Add-ons server rework and incremental updates
How add-ons are uploaded and downloaded has been significantly improved. When using 1.15.6 and later, only the files that changed between versions of an add-on are uploaded or downloaded instead of needing to upload or download the entire add-on each time. This will primarily help large add-ons and users with slower internet connections, but everyone will benefit from being able to update their add-ons more quickly.
NOTE: This involved a significant amount of work to the add-ons server, and as such there may be bugs that we've yet to find. Please make sure to report any issues you have to https://bugs.wesnoth.org.
Campaign Credits
The way the credits are displayed at the end of a campaign has been updated to a cleaner, nicer look. Additionally, this should bypass the existing bug where it was possible for Wesnoth to crash if there were too many credits to display.
Fixes
Words Disappearing When Changing Language
Previously when starting Wesnoth with the English language selected and then changing the language to Chinese, Japanese, or Korean, some words would disappear from various places until Wesnoth was restarted. This has been fixed, and words should no longer disappear when changing the language.
Newly Introduced Issues
Other
Minimum Boost Version
When building wesnothd with database support enabled, Boost 1.66 or later is now required. When building wesnothd without database support, the minimum required Boost version remains 1.56.