First up a little about graphical settings,resolution and controls. Game is coded in flash so no native gamepad support you need to use joy2key,xpadder,etc for that. The max resolution you can pick is 1280x720 which can be annoying if your a number guy like me who wants the best but at high quality it looks great on my 1080p 32" t.v. You also get 3 levels of quality low/med/high which if you've ever played a flash games you know will add higher levels of AA to smooth out the graphics but is also more demanding at high quality 720p its jaggy free and my main pc runs its no problem at that settings but being non gpu accelerated flash even with my i7 920 2.66ghz I still get some slowdowns when a lot of things are going on screen other wise its runs full speed during everything else so it doesn't negatively affect the experience in any large way its a minor fault. On my laptop with a core duo 1.3ghz its slows down quite a bit more. On the laptop I can run it at 720p but have to bump the quality down to low which adds a lot of jaggies to the game and the slow down happens a lot more often during regular gameplay but it defiantly perfectly playable and you can drop the resolution very low and it being a 2d flash game if you can run 2D flash games on the web this will run for you. In fact there is a Binding of Issac demo of the first 2 levels and some of the items and bosses of newgrounds so you can check that out below.
Game play wise It plays kinda like classic nes Zelda with grid based dungeon maps and you can walk in 8 direction with wasd and fire unlimited amount of tears in 4 using arrows keys or mouse there is no standard melee attack. You have a limited amount of bombs that you can be used to damage enemies(a well placed one can be used to wipe out hordes of enemies or seriously damage early bosses)or destroy rocks that block you from gaining access to key,hearts,treasure chest,etc. They will also sometimes advert open up a passage to a secret room which can contain a random item or a bunch of coins among other things. Each level has an special item room which will give you a power or item to help you on your journey. There is a sub boss and of course a main boss you most beat to proceed to the nest level you will be awards a powerup after beating each boss
The main thing that makes it so great is the rogue like element in that everything is randomly generated each time you play. The dungeon layout,items,enemies, and bosses will all be randomly determined from a large pool of items and bosses that you unlock more of the more you play so no two play through will be exactly alike. Death is also permanent in the game so each time you die your back at square one as there are no save points and no second chances. That combined with the random nature of the game means you can't simply memorize the dungeon layout and go for the best items and avoid rooms. This makes the game quite challenging and you will die a lot before you win but that only makes the victory all that more satisfying.
If your expecting an easy game that hold your hand the whole way and give you all sorts of hints( none of the items or power ups are explained in the game only through repeated playthroughs and experience can you find out what they do) and help look elsewhere personally I find the difficultly refreshing in this era games that you can breeze through with minimal effort. I personally died over 50 times and played over 8 hours of gameplay time before finally beating the last boss although I'm not even close to done yet still have more then half the items to unlock and you must beat the game several times before you unlock the true last boss each time you win you unlock a whole new dungeon floor up to 3 times I believe and the game will ramp up in difficultly after you beat it a certain number of times so there's a lot of content here if your willing to take to time and effort to master the game.