The open-source, community-maintained game Simutrans uses the Artistic Licence 1.0 (AL). I know many people regard this as a poor choice, but the core of the game was written as someone's spare time project in the 1990s, so it's two decades too late for relicensing.* However, compiling it from source now requires several libraries that use the zlib Licence (zL). Simutrans has been careful not to distribute those libraries with its source code, because of the difference in licences. This is confusing for newcomers, especially since there are many possible combinations of game versions and library versions, which do not all play nicely together. However, licences can be different, but compatible. Are the AL and the zL compatible for this purpose?
There are several answers here that address various compatibility issues, but none deal with this particular combination. The "choosealicense" website has a blank space in the "same license" column for both these licences, suggesting that neither requires that it be distributed only with other code from the same licence.
Note that we are talking about the Simutrans source and the library binaries and source; it seems to be well established that a zL binary can be integrated into an AL binary. The zL also seems very permissive, and does not pose any obstacle. So it comes down to the notorious clause 4 of the AL. Yet it seems to me that clause 4(a) was written to cover precisely this situation:
the software is being modified in accordance with the wishes of the Copyright Holders, so what is being distributed is the Standard Version source code in the future;
all that is necessary is to make clear where people of the future can obtain the last source code revision that does not include the zlib libraries (the Standard Version of the present).
However, IANAL and would welcome an answer from someone with more expertise.
*N.B.: This also means that the clauses 3(d) and 4(d) of the AL cannot be used, because many of the Copyright Holders are uncontactable.