As Carlos' answer left little room to improvements I can only make an observation about the particularity of "tratar acerca de". Here it is:
Juxtaposition of prepositions may end up in ambiguity every now and then, so to prevent this we may want to use:
En este juego se trata de investigar y desarrollar la sociedad, suiguiendo los pasos de tu familia.
The auxiliar "se" comes from "tratarse de" (reflexive verb)
In this tweaked phrase you add up readability to the sentence as you avoid the juxtaposition of prepositions - the theory is that two prepositions are more difficult to read than only one. Example in English: to get over with.
And if you were asking about what if we omit "de" in the sentence please note that in doing this we are using another different verb. Let's see the three possible verbs that may confuse us:
- Tratar (treat) - Roberto siempre trata bien a sus huéspedes (Roberto always treats well his guests)
- Tratar de (try to) - María trata de comportarse (María tries to behave)
- Tratarse de (consist of) - En el juego se trata de descubrir al mentiroso (The game is about finding out the liar)
And sorry for this:
¿De qué trata el juego?
El juego trata de descubrir al mentiroso. (Here, in the question, we have already "tratar de" so now it means "consist of")
Hoy tenemos un juego que trata acerca de descubrir al mentiroso. (Here we need to use "acerca" to avoid the ambiguity though it creates another, two prepositions)
You may find ¿acerca de qué trata el juego? but it is anything but common cause we use the shorter form to ask this question but if it is the case, the normal answer would be "el juego trata acerca de descubrir al mentiroso".
This is a very good question as it contemplates the nuances of Spanish, we have seen how "tratar" does not only have a reflexive form (tratarse de) but another different meaning if we add up a preposition (de) and also the usage of "acerca" as a linguistic device to prevent ambiguity. I hope it is as helpful as it has been to me.
Spanish and Spain.