Doom 2, like Doom 1, is epic continuation of an epic game from no less epic John Carmack. Here you can play Doom 2 online for free.
So, how does Doom 2 differ from its predecessor??? Well own nothing!!! Doom 2 is the same Doom 1 with the same enemies and the same weapon. Only a double-barreled shotgun was added, which uses the usual rifle cartridges, but 2 at a time, and shoots 2.5 times stronger.
Also in Doom 2 we have new levels. If the first Doom was on episodes, then here in Doom 2 all levels go in a row.
Note: many people write a lot that the player does not move, only turns. In fact, the control is built as in counter-strike: a - strafe to the left, d - strafe to the right, w - forward, s - backward, space - acceleration, e - open the door, ctrl or left mouse button - shoot. Left to right - with the mouse, or <- -> on the keyboard.