Games intended to be run under Fidonet-era bulletin board software.
They're called "doors" because they were separate programs that would run on the BBS host. Since machines didn't necessarily have multitasking capabilities, the main BBS program would "shell out" and start up the door program, which would then communicate with the user. When the door exited, the BBS software would start back up. Hence a door -- an excursion from the BBS to the outside world.
Barren Realms Elite (BRE) is a 25-player strategic war game. The game is set in a universe which is empty except for a few planets. The player, as a baron under a great king, must expand the barony throughout the king's planet, taking advantage of natural resources such as rivers and mountains to become the ultimate baron.
In Solar Realms Elite (SRE), you rule a solar empire. The goal is to become and remain the most powerful empire. You can gain strength by buying forces, and you can gain size by colonizing planets. You start with 6 planets, and a little bit of money. You are required to feed your people and army, and to pay to maintain your planets and army. If you fail to do these things, disastrous results may occur. You are given 20 years (``turns'') of protection, during which you cannot attack or be attacked. You cannot perform covert operations (except Spy). This provides a way for smaller empires to build up their defenses and planets before they enter the ``real world''.
A series of online space-strategy games loosely based on the StarTrek realm, where players compete economically and militarily to dominate a universe.