Tunnels of Doom (ToD) was the first computer role playing game (CRPG) I ever played. Heck it was the first *role playing game* I ever played. It was 13 years old and I had never been exposed to any RPG like D&D or anything else out at the time, and I was totally captivated by ToD. I remember reading the description on the box and did not even understand half of what it was saying, but it sounded fantastic! I played that game for hours! I think I always played as the single-player Hero, and I always played Quest of the King.
I started with dungeons from 3 to 5 levels, then 6 to 8 levels, and finally worked my way up to a full 10 level dungeon. I remember when I found the War-Ball and Chain, that was my favorite weapon! It took a long time to finish, but it was really fun. I was careful to save my game often, since sometimes my computer would crash because I would bump the expansion unit connector. :-(
Good times! Try a 5 or 6 level dungeon. Be careful and go slow. Make sure you have rations so you can heal, and don't trust those greedy Statues!