How can I play audio files via terminal. Afaik I've to install mplayer. Suppose I want to play list of audio files, is there any way to play all the files simultaneously via terminal?

Try "play file1.wav & play file2.wav & play file3.wav" etc

the command "play" is provided by sox, which means the above command won't work if sox isn't installed. But just about any of the main media players should work about the same. No need for "&" between each name though. Just run
To play all the files in a directory, just use a wildcard.
Another option would be to write all the filenames into a text file (one name per line, with full or relative paths) to create a playlist, then just load the list with
You might want to look into a more full-featured player though. There are quite a few good cli media players out there.

And remember "man commandname" will bring up basic documentation on most commands.

You can try mpg123. To read from a playlist (plain text, one file per line):

Or

I only added those because they said they wanted to play all the files simultaneously.

Ah, ok. If that's what the OP really wants.

But I get the impression that he's not a native English speaker and, considering the context, it's much more likely he really means "sequentially".

xmms2 is great if you have a library of music and like the idea of controlling a daemon instead of controlling an application that is only active as long as that terminal is active.