Code review comment for lp:~widelands-dev/widelands/bug-1803602-reveal-frisian-campaign

I think we can reveal it whenever the player has the necessary skills to play it.

I think we could also reveal the Atlanteans earlier, after Empire scenario 2, like I suggested on the forum https://wl.widelands.org/forum/topic/4327/?page=3#post-26178

Having 2 chances to reveal the Frisian campaign also solves the problem that players who already have played all Build 19 campaign scenarios will get access to the Frisians after playing Empire 4. Otherwise, they will have to know to replay Atlanteans 1 or to manually manipulate the campviz just to get at it. At the same time, new players can get still access after playing Atlanteans 1.