Total Annihilation
"Total Annihilation" was one of the first RTS games to feature radar that showed enemy units within its radius on the minimap. This added an additional element of electronic warfare to the game: players could construct radar jammers that prevented units in a small radius around them from appearing on radar. Mobile radar jammers could be used to create surprise attacks, necessitating the deployment of scout units on a regular basis to reveal said units visually. In addition, radar jammers could disguise the presence of visually cloaked units, such as the commander or land mines. Radar fields rendered cloaked units detectable; a radar jammer could make said units undetectable until the radar jammer was destroyed. "Total Annihilation" was also one of the first RTS games to point the way towards battlefields with hundreds and thousands of units. Previous games could field a hundred units or so. However, Total Annihilation initially permitted 250 units per side which was later patched to 500. A third party patch allowed up to 5,000 units per side.
Submarine TITANS
"Submarine TITANS" has the unique distinction of being the only game in the RTS genre where the entire realm takes place fully underwater. It is also the earliest RTS to have a full-fledged spectator feature for single and multiplayer and also the only RTS of its time to have an AI which could, when so instructed, play the entire game for the player, handling combat and building on all sides. This game is also one of the very first RTS games which had fully user-editable AI scripts, including an extremely detailed manual included on the CD on how to mod your own AIs. The game lobby allows a wide range of options, such as removing unit number limitations, starting resources or starting tech level. It also comes with a fully functional map editor, which can create both multiplayer maps and scripted missions and campaigns.