Okay, so what is Myth? As the box says, it's a fully cooperative fantasy game. The simplest way I can describe it is as Zombicide but with fantasy monsters instead of zombies. The system is fairly unique in the sense that none of the other dungeon crawlers I've played has a system like this.
Instead of having fixed abilities, heroes have a personal deck of cards that define what abilities they can use. At any time, you draw 5 cards out of this deck and you can use whatever actions/attacks you have in your hand. However, if the players(and yes, I'm referring to the team) use too many Action Points, this causes the Darkness to trigger and spawn minions. This is bad in general. In general, I find this helps to even the balance between having too many players and having too few. In Zombicide, if you ever went into a mission with only 2 characters, it was suicide most of the time. However, in Myth, if you have too many players, the darkness will be triggering perhaps 2-3x during the players turns.
With that being said, I'd just like to go into a short sidenote about the rules. The rules; as given in the box, SUCK. OMG, they are very literally the WORST rules I've read in ages. Maybe ever. And I'm not even using the hyperbole version of literally here. I can not remember a WORST written set of rules ever. Even old FFG rules; which were complex and involved a lot of page flipping to find out what the hell was supposed to go on, are better than this. How on earth have these people even managed to write a tabletop wargame and produced this pile of crap rulebook? Not only are terms just not defined in the rulebook, like courage. Wtf is a courage test? When do you take it? It would be nice to have it clearly stated in the rulebook that Courage tests are only taken when certain monsters require you to take them (as stated on the monster card). BOOM, instant understanding. Instead flip through the 60+ page rulebook and no mention of when to take or how to take courage tests. And trust me, that isn't even the only instance of non-defined rules in the book. This rulebook is crap and to be honest, I know there's a FAQ out there but not everyone is going to go and look for the FAQ while in the middle of a boardgame session. And the quest cards...some quest cards DON'T EVEN EXPLAIN the quest properly.
This rulebook is SO bad, that Megacon is ACTIVELY hurting their game by not reprinting a new rulebook and putting it into the newer editions of the game. Even if it means you have to unbox and pack everything again, this really SHOULD be done. I can understand why so many people were saying the rulebook was crappy right after they received the game and I'll have to echo them on this. Megacon, go print out a new rulebook or print our your FAQ and insert it into EVERY copy of the game. Trust me, this would only be good for you in the long run.
With that being said, I like the gameplay. Even though we screwed up so many things in the game; again due to a really bad rulebook, I could see where they were trying to go with this game and it IS fairly interesting. The gameplay can be brutal at times, which is always good in my book. There's also item-farming in this game, which I guess helps make it more replayable for some people. It's a lot like D&D in a way but without needing a DM. Kind of like the D&D dungeon crawling boardgames, but with a totally different mechanic.
As it is, I think this is one of those boardgames where my current group of friends would definitely be able to sit down and play for a full day. Even with our crappy understanding of the rules, we went through 3 different quests and we enjoyed it fairly well. You have the option to do stand-alone quests or you can do chained quests, which are all linked by a story. Those usually take much longer to complete and are recommended to be played over several play sessions.
Also, the miniatures. I think I can't really talk about Myth without describing the miniatures as well. The minis are pretty nice; if not the standard fantasy style, but they are pretty detailed for boardgame minis. My only real issue is that some of the swords/edged weapons are pretty blunt and not at all like a sword or weapon. Instead they're kind of like a shapeless mass at times.
Overall, this is a fairly decent game that has one major flaw; which is the rulebook.