I don’t know what “fossilized algae” refers to

Looked it up:

Nobel found that when nitroglycerin was incorporated in an absorbent inert substance like kieselguhr (diatomaceous earth) it became safer and more convenient to handle, and this mixture he patented in 1867 as “dynamite”.

Diatomaceous earth consists of the fossilized remains of diatoms, a type of hard-shelled microalgae.

https://en.wikipedia.org/wiki/Alfred_Nobel#Nobel_Prize

https://en.wikipedia.org/wiki/Diatomaceous_earth

Well, there’s two ways you could interpret that:

• As you say, ‘shelf life’, how long they can sell the game with their voice in it
• Or, ‘voice time’, as in, contracts are negotiated in total duration of voice lines. Exceeding that number requires renegotiation.

I suspect it’s the latter as that is more similar to how voice work is already done, to my understanding.