You can write pseudo code any way you want. Usually you only write pseudo code for yourself, so the only requirement here is to be able to understand what you meant when reading it later. If writing pseudo code for others to develop further you have to be more careful expressing yourself so they can understand what your half-thoughts. If they don't understand they will either implement it wrong or not complete, or perhaps they will just quote you and reply "what are you talking about?", so you have to explain more thoroughly. Pseudo code is about explaining in simple structures what the code should do, it is normally done using many of the keywords of the programming language, only much simpler. So you're not writing good English with full sentences and wide descriptions, and you're also not writing code that can be compiled and executed - but something in between.
That is the general description of the application, and has nothing to do with pseudo code. Writing pseudo code requires programming knowledge, if you don't know how to code you also can't describe how coding should be done, neither for yourself or others.So, a game to do with space needs a planet right?
So how do you make that and say that in pseudo?