Levels can get slightly repetative, also its an incredibly old game, but all of Heretic's problems were present in Doom (and even worse).
This game brings back great memories.
A while ago, ages ago, I got my first CD-ROM computer, it was great. The centrepiece of the software that came with it was a game called Doom. I had heard loads about it and was eager to play it.
The problem was that I was very young then, and my parents thought that a game like that would encourage violence in me, so I was banned from all first person shooters before I'd even seen one in action, let alone played one.
Not that that stopped me, whenever their backs were turned I played Doom, it was great, then I completed it, I was bored, I didn't feel like playing it again.
That's when I came across another game - Heretic....