It's funny it's kind of a small hump to get over at first but the game is actually SO simple. You have six green dice (five? I forget) for each investigator. On a turn they can either chill at the museum (and buy stuff or regain health) or go to any of the adventure cards. When they go to an adventure card they have to roll the symbols indicated on those cards. Sometimes there's only one part -- maybe something that requires you to roll a Terror, Lore, and 3 Investigation points. When you roll you'll either hit it and pass the mission and get the reward, or miss it. When you miss you have to dump a die and you can "save" one die and then continue rolling with your remaining dice. Some missions have multiple parts, there you can only beat one at a time. And in some they're numbered I, II, III, and there you have to do those parts in order. Any dice spent go away for the turn. Sometimes you will want to roll more dice, and this is what items are for -- they let you add the red and yellow dice to your rolls. If you're unable to complete the quest you get the penalty (usually losing life or something).
Keep going around like that and trying to rack up Elder Signs to win before the baddie gets enough Doom Tokens to win. There's also fun little things like monsters who add more things to do on a mission or things that lock dice, but that's the heart of it. It's Yahtzee Arkham Horror.
