|Image Source: Stay Alive! page 71, (c) Monte Cook Games|
Horror Mode is one of the many "bolt on" rules introduced in the original Cypher System Rulebook and carried forward in both the Revised edition and the Stay Alive! horror themed book. It's a simple enough rule where the range for player rolled GM Intrusions expands beyond natural 1s. As written it can be really useful for horror games and really help to build tension as the rolling of dice becomes fraught with the risk of a GM Intrusion without the balm of XP.
A while back I had tried an alien invasion horror survival game I called Invasion! It stumbled early on due to players being unable to make it and I ultimately shut it down rather than try and force it to work with an uncertain roster of players. Continuous stories really require a strong recurrence of the cast at the table, so I felt justified.
Recently I have been prepping to reboot and try again, and part of that is a conscious decision to look at what rules I could add or manipulate to further add to the tone and feel of their weird idea of mine. Horror Mode seems like a good choice but the way that it ebbs and flows wasn't what I wanted in my game. Instead I wanted a slow pressure that would build reliably over time as the alien invasion pressed onward. I built a timeline of events that would take place (assuming the players don't find ways to slow the aliens down), and in the process I had milestones that would put pressure and stress on the setting and characters. It started to resolve that as the aliens hit their milestones things would get more dire for the colonists.
Horror Mode is the perfect fit here, but at a much slower pace. Days will pass as the aliens execute activities and so days will pass between increases in the GMI range due to Horror Mode. The players may experience several sessions at a GMI range of 1-2 until another alien milestone is hit, permanently raising the range to 1-3. The players may also decrease the range by setting in motion their own actions to either set the aliens back, or make their own positions stronger to either counter the aliens or escape the planet.
By slowing the increases in GMI range for Horror Mode, and allowing player actions to help roll that range backwards I hope to create a palpable sense of slow burning dread that will help motivate the actions of the characters. Slowing the speed at which Horror Mode ramps up and down is a minor change, but I think it can pay off for Gamemasters who are looking for a very specific slow burn experience at the table.