Hacking the Surprise Mechanic.

I really like the surprise mechanic.  Though I’m not normally one to tinker with mechanics too much I’ve been thinking about tone appropriate mechanics for my Space Trash TM setting.

Uh-oh!  Someone rolled a '1' for surprise.

Normally each party in an encounter has a 1-2 in 6 chance of being surprised; easy. (I love it when both parties are surprised, it leads to some great comedy). It’s a really simple way for determining how encounters begin and is easy to modify to get a sense that one’s character is a perception ninja without having to get into skill systems as I will describe.

Things that significantly enhance your ability to detect foes before they detect you decrease your chances of being surprised by one step. Due to his experience and keen senses the ranger will notice opponents before they notice him therefore he has a smaller chance of being surprised than they do.

Things that make you harder to detect (but not undetectable) increase the chances of the other party being surprised by one step.  The Ranger is good at sneaking around unnoticed so is more likely to surprise foes.

How the f$%k did we not see them standing there?

These conditions stack, and cancel each other out as appropriate.  E.g. If you’re about as good at sneaking as a ranger*, but the other party is a warborg with amplified hearing, these cancel each other out, back to 1-2 in 6. 

In most cases the basic chance of surprise for both parties is 1-2 in 6.  The Ranger is well skilled at both noticing the tell tale signs that there are foes nearby which reduces his chance of being surprised to 1 in 6.  His skill at escaping detection by being stealthy increases foes chance of being surprised to 1-3.

Other conditions may modify this, which may be magic, tech or skill. For example a Chem Ranger wearing motion-detecting goggles further increase his chances of detecting foes first, which reduces his chances of being surprised one more step from 1 in 6 to 1 in 8.

The same Chem Ranger wearing a stealth cloak increases his chances of surprising his foes one more step to 1-4.  A ranger wearing both elven boots and an elven cloak has a 5 in six chance of surprising foes, whereas a normal dude wearing elven cloak (harder to see) and boots (quieter) would have a 4 in 6 chance of surprising foes.

This idea can be applied across all situations.  For example as a reskin of the ranger surprise skill a hotshot smuggler pilot may have the same modifications to surprise chances while piloting a spacecraft **.  If the craft also has active camouflage then the chances of sneaking up on another vessel increase so the other party’s chance of being surprised increases and if the vessel has advanced sensors then your chance of being surprised decreases.  The presence of gas on a battlefield might increase both parties chance of being surprised.

Other conditions may negate the need for a surprise roll.   If a thief was moving silently in total darkness, in a breezy room then there is no need to check for surprise IF the move silently check succeeds, otherwise do a surprise roll if it fails (you might want to pretend to roll for surprise anyway if the move silently succeeds). 

*I’m considering a new house rule that assassins get the same ability to surprise opponents as a ranger (this does not change he assassin’s chance of being surprised however).  Combined with the d6 hit points it may be time to step their xp up to the next bracket.

**This would potentially be an improvement on the WhiteStar Pilot, the abilities of which are too similar.