Let see if I got this right.

I am completely new to keyboards but always wanted to play one. A friend of mine bought an Alesis 49 and I am fascinated. Just as I was looking through this subreddit I saw that MIDI keyboards allow me to use softwares like Synthesia.

Does that mean I can play a song using the software just like I play, let's say, Guitar Hero?

Sorry if that sounds dumb. I have a dream in which I can play Pokémon Medleys using a keyboard and I am doing my search to make it come true.