With the introduction of Lucy Opendev, players now have the chance to experience everything that saboteurs can do. 

Unfortunately, what these shady characters can actually do is rather limited and possibly inconsequential in the grand scheme of things. I believe a few changes are necessary to improve the in-game experience for both the detection and stealthy styles of play.

This elusive line of units comes in the late Medieval with the introduction of the Saboteur. The Haudenosaunee Emblematic Unit is an Early Modern gunner upgrade to the line . 

This line boasts below-average combat strength, average production costs (of their era), and the stealth trait as their most notable aspect.

Stealth units can cross the closed borders of other cultures during peace and can be detected by any patrolling units or quarter with a detection range. A player could assume a stealth or saboteur unit could perform actions to hinder the culture they infiltrated by ransacking unattended quarters and resource extractors. 

However, this is not the case as stealthy units cannot move adjacent to or inside quarters (including extractors) without being detected. 

This leaves saboteur units few possible actions that include information gathering, surprising unprepared combat units (during war), and preparing to ransack things when war breaks out... all the while risking accumulating trespassing grievances which can stack up quickly. 

Saboteurs can not even move onto un-exploited resources:

Saboteurs cannot move close or on-top of exploited resources far from civilization:

What needs to change:

I feel saboteurs and other stealth units should live up to their namesakes and perform nefarious acts to other cultures during peacetime. This involves being able to ransack resource extractors and un-fortified quarters outside of a city's walls without incurring grievances. The expansionist affinity could also come into play to steal territory from unprepared or unguarded cultures 

The mechanics are already in place for detecting stealthy units that currently include all quarters (including extractors) with forts, garrisoned units, and patrolling units having larger detection radiuses. I am in favor of increasing the fort, garrison, and patrolling unit detection radius if only to provide saboteurs the opportunity to ransack unprotected quarters and resources. Some cultures with fortification bonuses like Carthage, Poles, and Mycenaean would have an edge detecting in this regard. 

As the system currently stands, a culture during peace need not worry about their cities or resources nor do they need to expend any resources to protect them. Altering the system as mentioned above would increase the value of patrolling units, forts, and garrisons in general during peacetime which I believe is warranted. 

I encourage everyone to build a few saboteurs and test what they are capable of doing during the Lucy Opendev. Information gathering is very useful, but the current limits are very restrictive to this style of play. I wish to see nefarious acts and subterfuge become a useful aspect to employ which can make for a better overall experience. 

- RNGzero from Reddit and Discord 

aisle9 wrote:

I don't mind them ransacking things while in peacetime, but it should cause grievances if they find you ransacking their stuff.

If a stealth unit is detected, a trespassing grievance is generated for each occasion found. 

It may be difficult to properly accuse another culture of ransacking (if it did occur). I could see a status effect placed on a saboteur after ransacking that if caught would facilitate a harsher grievance then just trespassing. 

I'm so glad we can finally discuss this matter. Though I do believe that someday this game will have full-scale intelligence & espionage contents, Saboteurs and other stealthy units are currently meant to do shady operations. But they are bit restricted from engaging in espionage unless there's an ongoing war.

Then let's just imagine what would happen if these stealthy units are allowed to do some harm against peaceful nations. What if saboteurs can ignore closed border and ransack peaceful neighbors as long as they aren't caught doing illegal things?

Assumptions

1. Vision sharing between alliances or vassalage includes reveal of stealth units. Therefore, destructive acts of these units are not allowed in such relations.
2. Being able to ransack something means the other party holds the right to attack and expel the offender in any case.
3. Trespassing or ransacking in stealth is considered illegal and generates a grievance if caught.
4. Attacking or killing unlawful armies in the 3rd assumption is considered legal and does not generate a grievance.

With these assumptions, we can safely skip some discussions regarding the behaviors of these units in a war, alliance, and vassalage relationship, because all assumptions are either nullified or self-evident. Let's move to espionage during peacetime.

Counter-espionage will consist of 2 things. Catching stealth trespassers and vandals. If you can build enough garrisons or catch trespassing saboteurs with patrolling armies, they won't be able to reach their target. If you found someone ransacking your quarters, you would be able to stop it by initiating a battle and claiming a victory. And these measures are directly related to 2 treaties. One is about trespassing and the other is about aggression. Open Border changes everything about trespassing. Since crossing the border is always legal, sending saboteurs in to do some shady operations is also legal, as long as you don't get caught ransacking their assets. Therefore, open border treaty removes one important tool from the defender. Of course we can make a special rule like "stealth units can't legally cross the border even with open border treaty". But once someone puts stealth units and non-stealth ones in a single army, such rule will either include lots of loopholes or feel too arbitrary. Furthermore, Non-Aggression Pact will require another special rule. Because of the 2nd assumption above, now the defender should be allowed to attack a trespassing (if closed border) or ransacking army of the offender, ignoring the NAP. (there's also a simple way forbidding any ransack under the NAP treaty but lots of players wouldn't want this)

Possible exploits

Cold War: Seems okay

Isolationism: Should be okay as long as you can attack trespassers

Unfriendly Passage: Can send countless saboteurs without generating any grievance, Any attack on saboteurs will trigger a grievance as long as they aren't ransacking something

Amity: All exploits from 'Unfriendly Passage', Can surround and protect a ransacking saboteur with other lawfully travelling saboteurs

NAP related exploits would be relatively easier to fix. Either changing the content of NAP into "can't attack each other in neutral areas (but attacking trespassers is legal regardless of the border policy)" or making ransacks interrupted by getting blown from stealth (so that sabotages can be stopped peacefully even though the defender can't expel them by force).

Open Border related exploits would require more works. Maybe more detector sources or longer detection range will be required to make it possible to cover most of the important areas with detection range, since border check strategy wouldn't work without heavy changes in the way border policies work.

Quick idea 1) Instead of implementing stealth by unit trait, use status. Once saboteurs get spotted from patrolling armies or enter detection range under open border, remove the stealth status and don't give it back until they return to a friendly area. With this, border check strategy can work since garrisons will remove the stealth status and disable saboteur's stealthy ransack ability.

Quick idea 2) It might be possible to solve some diplomacy-related issues by granting privateer-like status to stealth-only armies, so that they become independent from any treaties or relations.

I love all these suggestions. Having saboteurs and spies is such a cool idea but right now, they just feel like they're in a weird place that makes them useless. 

I also found the special privateer ship, and it should absolutely be able to cross borders in the same way as well.

There would definitely have to be some status effects to properly associate grievances within the espionage system. This could include opening up some new treaty options to cover such nefarious antics between allies and enemies. 

Atlas47 wrote:

So the stealth melee units are good if they get killing blows (assassinations, thematically), since then the enemy has to move a unit into the (presumably bad, since it was easy to get a killing blow) spot just to see them. Perhaps that is the point of them, and being invisible on the main map is just a bonus?

Also I agree that Outposts being uncontrolled territory to non-alliance relations would be good.

I think it is the opposite. 

Saboteurs are naturally fantastic vs. ranged/gunners as the other side must have vision before attacking, yet the most prominent unit of the medieval era are melee cavalry. Before stealth units gain ranged/gunner attacks, they must trade blows (melee) with their target while likely having lower str (w/o significant terrain advantages).

The main goal of stealth units is not to engage in combat while gathering information and sabotaging quarters.

If saboteurs are engaged, the player has a choice to either decidedly retreat/lose without much resistance (just hides) or fights with gorilla tactics. Despite the choice, I do not think a stack of saboteurs would offer too much challenge to a prepared patrol. Against an unprepared patrol, a stack of saboteurs would have the numbers, chose of location, and potentially the terrain advantage to adequately handle proper units.  

Privateers are not stealth units as they show up as normal on the map and in combat with only their allegiance in doubt. However, these should eventually upgrade into a stealthy unit in a later era. 

Other stealth units such as the German's Uboat, Industrial stealth units (Generic, Mexican Soledaderas, and Austro-Hungarian Evidenzbureau Agents), and contemporary upgrades may play differently due to the different units available and environment occurring in later eras.  

Stealth units involvement can give a good challenge to maintain territory and i also agree that it should not be effected by diplomatic treaties.

It can also have more units like spy units like spy drones and an intelligence centre or constructing a whole spy network.

There can also be intelligence warfare like cyber attacks, intrusion attempt by more units.

I think that these stealth unit should have extra ability like

Train rebels: the unit can infiltrate city and do it.

Increase cultural influence

Decrease war demand

Stealing science, production and money

Disrupt trade