Whom does he play game to get?

The OP writes

I play game that I save someone, and someone asks whom do I save.

The Present Continuous tense is used if the game is being played while the speaker is watching.

1. Who are you saving? (most common)

The speaker could make a slightly longer question:

2. Who are you trying to save in the game?

Use the interrogative pronoun "who". If this were an English exam then I might suggest using the formal equivalent–whom–but because the context is informal, it would be inappropriate to use "whom". 3. Whom are you saving? (too formal)

If the act of saving occurred in the past and is completed, the question would be

• Who did you save?
  Who did you try to save?
  Whom did you save?

The whole sentence needs re-writing I think to clarify what is going on. I suggest:

In the video game which I am playing, I saved someone and I was asked who I had saved.

The main changes are (1) I clarified it is a video game, (2) I put save into the past as it must have happened before they asked you, (3) I made the last part passive to avoid repeating someone which would be confusing as they would be referring to two different people.

I am sure there are many other ways of re-writing the sentence.