It's like an RTS, but you only have 4 units, and you've got fairly close moment-by-moment control over their actions.

It's continuous, not grid- or turn-based like X-COM.

A lot of the maps feature police, antagonistic to all syndicates, and civilians, whose death or injury can attract the police. This aspect can require some management. I don't recall this kind of mechanic from any of the RTSs I played around that time.

Also worth noting: it ran in 16-colour 640x480 VGA (or maybe it was 640x400...), so it looked nice and intricate. Sure, you take a slight colour count hit compared to 320x200 - but UK games artists in the early 90s were well practised at dealing with that, after years of doing ST and Amiga games. (The Amiga had a 32 colour mode, but it came with a performance penalty.)

It's gameplay was very similar in practice to that of Grand Theft Auto, the first top down one, except it was years ahead.

There was also a money and equipment/weapons buying and upgrade system that was very cool, similar to some of the top down shooters or racing games.