The spiders can be killed with any weapon. You can kill it with a couple hits from your sword. You can kill it with a bomb explosion. Or you can freeze it with ice magic and then blow up the resulting ice block with a bomb. The latter method is probably the easiest, since the ice magic lasts for a good second or two in front of you.
If any of you want the demo before it gets put up on the site, reply with your email address (or PM it to me) and I'll send it to you.
A couple notes:
There are some puzzles there that don't do much (some that do though). This version wasn't meant as an "almost-complete first dungeon" or anything like that. But rather it's where I left off when I stopped working on it. Meaning some incomplete areas, and some things done to make it easier for testing purposes. However, as I mentioned before, you will have to solve one puzzle in order to reach the boss in this version. I think the dungeon in this demo has about 8 or so rooms. The finished dungeon was planned to have around 20 rooms.
I've got to say though, I never expected this many enthusiastic replies. I almost feel like getting to work on this right now! Sadly, I need to get some sleep.