Wolfenstein 3D is now available for free online. But is this version any different than the original?

Solution 1:

The original Wolfenstein had six episodes to play. The browser version only has 3.

Episode Select screen for Browser Version:

Episode Select screen for the original:

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Essentially, the browser version is only half of the original, with all other aspects appearing to be the same as far as I can tell.

Solution 2:

I passed countless hours on this game 20 year ago and, apart of some change in the READ THIS! section, I did not notice any changes to the gameplay and graphics. I did not remember the music because I did not have a Sound-Blaster card back then. (Hello PC speaker sounds.)

Along with the release of this browser port there is a Wolfenstein 3D Director's Commentary with John Carmack. As specified in the beginning of this video, you can watch John Carmack playing some levels on the original DOS version. A comparison of this video and the game reveals that the browser port seems faithful to the original.

Solution 3:

This is almost the exact replica, it was one of the only games I did play, but let me see it seems it lacks the LIM cheat code¹. Thanks to the cheat I did not have to disassemble the code for a God mode.

^{¹ LIM cheat code - Pressing L, I, and M simultaneously at any time during gameplay wil give you 100% health, 99 ammo, all weapons, and both keys (even if there are no keys in your current level). However, doing this will also reset your score to 0, and you will not be eligible for the high score list.}