Hey guys, I'm mildly interested, simply because of how the game is well recieved and reviews are positive....
What is the point of the game?
Can you save?
Is there progress of some sort?
These are all serious questions as I can't seem to understand the game.
Well, the point of the game is to win. I don't know if you've ever played a roguelike game before, but the basic idea of BoI is that you progress through a series of levels, gaining new abilities as you go, but if you die, that's it, you start over. Generally speaking, a successful run of Isaac takes less than an hour, so it's not like you're losing a ton of time when you die.
The game saves your position when you quit (at least on the PC), and you get the option of continuing from there when you start the game back up. However, you can't just save the game and reload it later on if you die.
The progress comes in the form of item unlocks and further levels that become available as you beat the game more times. The way the items work is that throughout the levels, you come across items that can do anything from simply boost your damage, to drastically change how your attacks function (homing shots, exploding shots, etc). As you reach different milestones, more items become available. You're not going to see every item every time, but the pool of items that you can get increases as you go.
As far as the level unlocks go, I don't want to spoil too much, but basically, when you first start the game, you're trying to get to a certain boss. Once you beat that boss for the first time, you get one of the games many endings. On the next run, you fight that boss again, but then the game continues on to another set of levels.