Oh, Isaac. How I love thee? Let me count the ways:

1) Upped the FPS limit from 30.

2) Huge number of items and different combinations of items are endless.

3) You're a naked, little child in the basement, unsupervised.

4) That feeling you get Brimstone the first time and absolutely wreck everything in your path.

5) A lot of items will end up destroying your run.

6) You can become a real doctor with a PHD.

7) You can be a little cat.

8) Stab everything if you find the knife.

9) Kill Satan!

10) Kill yourself!

11) Kill yourself! Again!

12) Be killed horribly a thousand times!

13) Can't wait for Afterbirth!

14) Kill the angels for giving you garbage items!

15) Be trolled by bombs, flies, Satan, store owners etc.

16) Cry on your enemies with explosive, giant, piercing, homing, stunning, charming, intimidating, slowing etc. tears.

17) So many enemies and a lot of deadly ones. Some rooms are just run-killers. You can still die if you're not careful, even if you have the best items, which makes for almost infinite replay-value.

18) You get better at the game, whether you want to or not.

19) This is the reason number 19.

20) Playing a new game is always fun.

What's not to like?

1) I forgot to feed the dog because I was playing.

2) Late for work for not sleeping enough because I was playing.

Oh, Isaac. How I love thee? Let me count the ways: 1) Upped the FPS limit from 30. 2) Huge number of items and different combinations of items are endless. 3) You're a naked, little child in the basement, unsupervised. 4) That feeling you get Brimstone the first time and absolutely wreck everything in your path. 5) A lot of items will end up destroying your run. 6) You can become a real doctor with a PHD. 7) You can be a little cat. 8) Stab everything if you find the knife. 9) Kill Satan! 10) Kill yourself! 11) Kill yourself! Again! 12) Be killed horribly a thousand times! 13) Can't wait for Afterbirth! 14) Kill the angels for giving you garbage items! 15) Be trolled by bombs, flies, Satan, store owners etc. 16) Cry on your enemies with explosive, giant, piercing, homing, stunning, charming, intimidating, slowing etc. tears. 17) So many enemies and a lot of deadly ones. Some rooms are just run-killers. You can still die if you're not careful, even if you have the best items, which makes for almost infinite replay-value. 18) You get better at the game, whether you want to or not. 19) This is the reason number 19. 20) Playing a new game is always fun. What's not to like? 1) I forgot to feed the dog because I was playing. 2) Late for work for not sleeping enough because I was playing.