Summary:
- If you've used it, attribution is required.
- If you've created a new separate artistic element from it, you must distribute your contribution.
Explanation:
It comes down to how you are using the font. From the
license text:
ShareAlike — If you remix, transform, or build upon the material, you
must distribute your contributions under the same license as the
original.
Using the font as is to display the player score does not remix, transform, or build upon the material.
Creating a new font with gore drips for displaying damage taken would be transformative. The new font would need to be released under the same license; the game uses the derivative font, but is not itself a derivative font. Attribution is still required in some context with the game, but the game itself is not subject to the CC license.
However, let's say the gore drips weren't part of a new font itself, but instead were added separately (perhaps as a special effects shader). In that case, the original font is not being transformed directly and is not a "separate artistic element". Because there's no new font that could be released, the "distribute your contributions" clause would not be applicable.
And in all cases, Creative Commons isn't a great license choice for software and creativecommons.org recommend against using it as such:
Can I apply a Creative Commons license to software?
We recommend
against using Creative Commons licenses for software. Instead, we
strongly encourage you to use one of the very good software licenses
which are already available. We recommend considering licenses listed
as free by the Free Software Foundation and listed as “open source” by
the Open Source Initiative.
Unlike software-specific licenses, CC
licenses do not contain specific terms about the distribution of
source code, which is often important to ensuring the free reuse and
modifiability of software. Many software licenses also address patent
rights, which are important to software but may not be applicable to
other copyrightable works. Additionally, our licenses are currently
not compatible with the major software licenses, so it would be
difficult to integrate CC-licensed work with other free software.
Existing software licenses were designed specifically for use with
software and offer a similar set of rights to the Creative Commons
licenses.
Instead, they go on to say:
While we recommend against using a CC license on software itself,
CC licenses may be used for software
documentation, as well as for separate artistic elements such as game
art or music.