So we are dealing with gold box AD&D games here in first edition. This had a couple of new classes the ranger and paladin, not sure if they were in azure bonds. The big thing about it was they expanding the map beyond the 16x16 limits they had previously used. From there it seemed the same game as all the rest, with a bit of a level cap increase.
The storyline is the party has been magically transported to the a city in danger, to help the towns folks. They have no equipment at first but are quickly given some gear by the town elders. That all is pretty standard for this time of game. It's worth noting equipment never transfers over even if the party members have been leveled through Pools, hillsfair and secrets. From there they are asked to stop the "Evil". I really cant remember the evil though it was something about a frozen army and possibly a lich.
The party are sent out to explore and ostensibly power up. this is where they enter the massive area of exploration that is the game. You can just kill and kill and sometimes hit the locations you need to travel to. Which would seem interesting but ends up being pointless as you never need to travel once you reach the portal zone. I did find a +6 set of leather armor in a drawer once but after that nothing really of interest. Once you reach the portal room you have a fight of decent difficulty for control of the portals. After this you can travel back and forth. There is a portal to the city you started in and eventually portals start opening that lead you were you need to go. One is to a old dwarf fortress that is taken over. Once you clear it you find an old dwarf that will heal and raise you for free, with no chance of con reduction. That sort of breaks the game as well as you are always near a portal and then the fortress and can just use him whenever you are in trouble.
The last fight of the game is the only one where you really have a challenge. I tried a couple of times only to die again and again. The third attempt I actually buffed for the first time in the game, and it was cake. One note give the ranger the giant slaying sword they have bonuses against them and he will kill a giant a round.