Rebelstar
Rebelstar is a turn based strategy game by Julian Gollop, originally released on the ZX Spectrum. The game revolves around an assault by the Raiders (humans supported by combat droids) on Moonbase Delta, which is guarded by the Operatives - all droids (in the single player version) or a combined human/droid force (in the two player game).
The objective of the game is to destroy ISAAC, the computer responsible for breaking the Raiders secret codes. The game can be won either by destroying ISAAC's central core, or eliminating all enemy forces in the base. The player can gain reinforcements by destroying three Laser Defence Computers located around the bas, this allows reinforcements to arrive a few turns later.
In the single player version, the level can be set from one to eight, each level increasing the number and power of the droid forces. The game has a inbuilt time limit, and the Raiders automatically lose if they fail to achieve either objective within the time limit.
The game was quite sophisticated for the time and hardware it was released, featuring multiple weapon and unit types, opportunity fire, as well as morale, stamina and encumbrance statistics for units. It is also possible to interact with the environment in a limited fashion. Some features could be destroyed by the more powerful weapons, limited ammo is available for weapons (which requre reloading), bodies can be looted, debris and bodies from killed/destroyed units slows down units moving over them, various objects can be picked up and used, certain objects provide cover from attacks etc.
However the game does have drawbacks. Due to the sheer size of the game, it was impossible to store the starting configuration in memory, so it was necessary to reload the game each time you wished to replay it. (In this era of emulation, this drawback no longer applies.) In the two player version, the odds are heavily stacked in favour of the Operatives, as there are only two access points to the area containing the computer core, which has a large number of Operative units within it, as well as the armoury. This makes it easy to mount a 'choke point' defence of the area.
Since the Raiders automatically lose if they go over the time limit, there is no incentive for the Operative player to leave the core area and engage the Raiders over the whole area of the base, and attempting to move sufficient Raider forces into position to attack the core area before the Operatives can set up the defence is extremely difficult due to the fragmented startup postions of the raiders.
Successfully attacking through a readied defence is almost impossible, due to the twin factors of the amount of firepower that can be brought to bear on the two access points (especially considering the opportunity fire feature), and the fact that killed/destroyed units hamper the movement of follow up units. This can lead to a frustrating game for the Raider player, unless the two players agree alternative victory conditions such as the time limit applying to the Operative player, who loses unless all raiders are dead when the time limit expires. The single player game does not suffer this problem, as the computer is far more aggressive than a human player might be, and actively engages the Raiders as soon as they enter the base.
Many of the features and ideas in Rebelstar would go on to be used by Gollop in the Laser Squad and X-COM series of games.