Suppose you woke up one morning to a world with no human beings around, no electricity, and no water.
Suppose: Your translation is correct, angenommen is the best choice here, but note that it isn't separated with a comma from the rest of the sentence.
You woke up: This is conditional type 2 and in German you use the subjunctive II (derived from preterite, as in English it's the simple past) or you can use the paraphrasing with würde. That is, "du erwachtest" or "du würdest erwachen".
Your version with "haben" is wrong for two reasons. First, this would imply present perfect and, second, aufstehen in present perfect is accompanied by "sein".
One morning: Perfect translation! Eines Morgens.
To a world: The right preposition in German is in. You wake up in einer Welt.
With no ...: This is the same as without which, in turn, is translated as ohne...
no human beings around: While around conveys the idea of having those people, well, around you, I would drop that altogether. You can still translate this with um dich herum or in deiner Nähe.
Note, there's no verb in your English sentence that convey the idea of bemerken (to notice, to realize).
Angenommen du erwachtest in einer Welt ohne Menschen, Elektrizität und Wasser.
Angenommen du würdest in einer Welt ohne Menschen, Elektrizität und Wasser erwachen.