Tech hexes give touching hexes better abilities. Bomb hexes can drop proximity shelled bombs,for example.Tech hexes are extremely useful for when you have armor hexes,but they are badly damaged.Tech hexes can regenerate health to neighboring hexes as long as there is at least 1 armor hex touching the tech hex. Missile hexes fire homing projectiles,but they only home in on something if an enemy enters the circle surrounding the projectile. Speed hexes can be used as anti-thrusters, which improve the ability to turn around when you have a tech hex touching(it may have maximum effects if the tech hex is touching a line of speed hexes,or optimized thrusters). I’m not sure if tech hexes have any effect on grow hexes,though.