I was ordered to travel to Mars.
I enjoy traveling among the stars.
When some people on Mars tried to open a gateway to Earth, they accidentally opened a gateway to Hell.
Many demons came through the gateway and many soldiers tried to stop them but they were bound to fail.
The demons killed the humans and turned them into zombies.
Now I have to kill them all before they get the chance to kill me.
I have to kill Imps, Cacodemons, Spiderdemons and Barons of Hell.
Sometimes I also come across Cyberdemons and I kill them as well.
When I come across a locked door, I have to find a key to unlock it.
A Cyberdemon is chasing me and it's trying to kill me by firing rockets.
I just used my rocket launcher to turn it into goo.
Every demon and zombie will be dead when I'm through.
A shotgun, plasma gun, chainsaw and other weapons are what I have to find.
I hope the demons don't somehow get to Earth or it will be the end of mankind.
By some miracle I've destroyed all of the demons and zombies as well.
I was able to complete my mission and I thank God that I didn't fail.