Semi-Guided LRMs are an alternate Long Range Missile type.
Arguably the most innovative result of the Free Worlds League's 3050s specialty LRM munitions research efforts, the Semi-Guided LRM debuted in 3057 just in time for Operation Guerrero. Working with the Artemis IV FCS compatible missiles as a base, League scientists developed a smaller LRM-sized version of the laser-homing technology of the guided Arrow IV missile. This allows Semi-Guided LRM flights to home in on a target "painted" by a friendly unit equipped with Target Acquisition Gear (TAG), enhancing their accuracy.
Much like the Narc Missile Beacon, the primary benefit of Semi-Guided LRMs compared to the more common Artemis IV is that only the TAG equipped spotter needs direct line of sight to a target, which allows friendly launchers to fire indirectly from cover. Other benefits are that standard LRM launchers can fire the rounds without modification, allowing units with lower volumes of advanced technology to still utilize them without requiring extra weight be devoted on any firing units.
The only disadvantages are semi-guided missiles are three times the cost of standard missiles and somewhat rare outside the borders of the Free Worlds League or among the forces of the Word of Blake. With unaided personal combat being the height of honorable Clan conduct, so far the Clans have not attempted to replicate the technology.
Semi-Guided LRM missiles can be fired as normal missiles using normal rules if no target has been tagged. Otherwise, when fired against a tagged target, these missiles ignore any target movement modifiers caused by the target walking, running, or jumping. These missiles also, if fired indirectly against a tagged target don't get the +1 to hit modifier that would normally be applied to indirect fire LRMs. According to Total Warfare errata, updated in 2018, these missiles also ignore terrain penalties, and the to-hit penalty caused by a moving spotter.
- TechManual, p. 231: "Semi-Guided LRM"
- Field Manual: Free Worlds League, p. 138: "Semi-Guided"
- Total Warfare, p. 142: "Semi-Guided Missiles"