TAC/SCAN is a one or two-player vector-based shoot-em-up in which players control a formation squadron of seven fighter ships. All seven ships fire at once when the FIRE button is pressed, producing a spectacular missile salvo.
The player begins the game with a seven ship formation and a supply of reserve ships (shown above the player score). The object of the game is to accumulate points by destroying enemy ships while avoiding incoming fire. As well as the main squadron, there are a number of reserve ships and an ADD SHIP button. This transfers one of the reserve ships into the squadron formation. The 'add ship' position continuously cycles between the empty squadron positions, allowing players to time the ADD SHIP function to place fighters at their desired location.
There is an additional way to add ships to the squadron. During the course of the action, player ships enter the playfield and intermix with the enemy ships. The player can capture these fighters directly into the seven ship formation by steering them into empty fighter positions. The player's missile fire DOES NOT blow up friendly fighters, only enemy ships.
When the player attempts to dock a friendly fighter into their squadron, they have the choice of any of the vacant positions. A special feature occurs if the player ship docks into the front-most ship position (marked with a red cursor). This causes the squadron formation to regroup into a different pattern. If the load position is occupied, a fighter is added to the reserve count above the player's score.
TAC/SCAN has two different battle sequences, with each presented from different perspectives. At the end of the first battle the squadron regroups and a transition sequence takes the player into phase two. This sequence consists of enemy ships appearing in the distance but quickly growing in size as they approach the player's squadron. As win the first battle, players have the opportunity to rendezvous with friendly fighters.
At the end of the second phase a space tunnel appears and the player must steer the squadron through the tunnel. Any fighter that hits a tunnel wall explodes on contact. A triangular guide is displayed during this sequence to indicate where the ship formation should be. If the player keeps the formation centered within the guide, no ships will be lost.
The game is over once all seven ship positions become empty, even if the player still has ships in reserve.
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Sega G80 vector hardware
Main CPU : Zilog Z80 (@ 4 Mhz), I8035 (@ 400 Khz)
Sound Chips : Custom (@ 400 Khz)
Screen orientation : Vertical
Players : 2
Control : dial
Buttons : 2
Tac/Scan was released during November 1982. It was the only Sega vector game to use a vertically mounted (portrait) monitor.
Rounds 1 through 7 :
Enemy ships : 100 points X round number.
Stingers : 1,000 points X round number.
Destroying 2 enemy ships with a single missile salvo doubles the point values.
Destroying 3 enemy ships with a single missile salvo triples the point values.
TIPS AND TRICKS
The most effective strategy for extending your playing time in Tac/Scan is to add as many extra ships as possible to your reserve (listed in upper-left corner of screen). Ships must be caught by the leading ship position which is further signified by a red colored underline in order to be added to your reserve. To begin capturing ships you must have at least one open position in your fleet; otherwise the game will not award ships (kill off 2 of your ships on the edges of your fleet at the very beginning of the game to achieve the highest amount of reserve ships during the first wave).
Wave one in Tac/Scan should always be played with a minimum of two ships in your fleet, with additional ships added as the levels get faster and harder. The second and third wave can almost always be effectively played with only two ships, and it is very important not to waste reserve ships in these two waves (saving those ships for the more dangerous first wave).
Always keep changing directions on both wave 1 and 2. It is very effective to destroy ships while turning on wave 1, and on wave 2 ships will have a hard time hitting you if you don't stay in the same position for very long.
The faster you fire, the shorter your shots will travel. Allowing a short pause between shots will allow them to travel the distance of the screen.