Picked up a medikit that you REALLY need!

This message, as displayed on PrBoom.

The original Doom source code included provision for a special message to be displayed when the user picked up a medikit while their health was low. Instead of the usual "Picked up a medikit" message, "Picked up a medikit that you REALLY need!" was supposed to be displayed.

Because of a logic error in the implementation, this message is never displayed. The following is an excerpt from p_inter.c:

     case SPR_MEDI:
       if (!P_GiveBody (player, 25))
           return;
       
       if (player->health < 25)
           player->message = GOTMEDINEED;
       else
           player->message = GOTMEDIKIT;
       break;

This section of source code implements the medikit powerup logic. If the player's health is less than 25%, the "Picked up a medikit that you REALLY need!" message should be displayed. However, the code which gives the player the extra health is placed before the check is made. Because a medikit gives 25% extra health, the player's health is always at least 26% before the check. As a result, the normal "Picked up a medikit" message is always displayed and the special message is never shown.

A fixed version of the code is as follows:

     case SPR_MEDI:
       if (!P_GiveBody (player, 25))
           return;
       
       if (player->health < 50) // 25 health + 25 from medikit
           player->message = GOTMEDINEED;
       else
           player->message = GOTMEDIKIT;
       break;

This bug has been fixed in PrBoom, Eternity Engine, most ZDoom-family source ports, the official Doom Classic Unity port and possibly others.