Cover Systems and Overwatch


Cover me – I’m going in!

Ostensibly a cover system, within the context of a generic turn-based tactics game, is to provide positional play options. It can also provide a mechanism for regenerating health (more common in shooters) and encouraging indirect confrontation of obstacles. If not the latter it can also encourage turtling: whereupon the player chooses not to move because there is no risk the player is willing to take to improve her position.

Games like XCOM: Enemy Unknown cover provides passive benefits, such as 1) stopping enemy units from flanking, and 2) reducing the probability for enemy units to hit them with ranged attacks.

What I find interesting is that a simple cover system can be replicated mechanically in other ways – cover is just frequently chosen because it passes both the realism/simulationist test as well as providing for some thematic tension.

There is no traditional cover system in Steam Marines 2. Instead units can directly suppress other units which apply ranged-to-hit debuffs. There are a number of benefits to this system over a cover system despite both affording a player’s units probabilistic defenses against attack:

  • Unlike traditional cover a player can stack her unit’s suppression, whereby a unit suppressed by one marine might receive a -15% chance to hit, two marines suppressing the same target might confer a -30% (or non-linear stacking) chance to hit.
  • It encourages units to be more proactive in terms of movement and fire, the core tenets of the Steam Marines series.
  • Expending ammunition to suppress a target is more costly than simply finding cover; Waiting too long to advance once suppression orders are given is a drain on ammunition (which is finite) as well as still allowing the reduced chance to take damage. Even if ammunition is not finite turn-based tactics games generally have weapon reload mechanics which should be taken into account.
  • Since suppression acts as an active cover system there is more granularity to the power scale of employing it tactically; Having a marine get -30% chance to be hit in cover is different from having a marine that can suppress a target for -30% chance to hit. In the first situation the mechanics encourage the marine to be on point and reduce the chance for all shots from all enemy units to land. The second situation encourages more positionally-minded play since the marine can only suppress one target, and it cooperates better with units that perhaps have a higher chance to hit but a less powerful suppression debuff. Thus getting all marines increased cover evasion in the first scenario breaks the power curve much more than buffing suppression for all marines.
  • It really emphasizes that Steam Marines 2 is about squad cooperation. A lone marine is very vulnerable, much more so than a lone marine in a traditional cover system.
  • It doesn’t have any finicky edge cases with melee units. A traditional cover system doesn’t provide any offensive debuff for melee units, but an active suppression system does – and should!

You don’t have to have one or the other, or even either or – you could have a hybrid system or something completely different. I just personally prefer a more active tactical system.

Aside: Suppressing a target who auto-retaliates and kills your marine completely fits in the theme of a brutal, challenging game. Auto-reprisal systems that trigger on direct attack as well as suppression also add a lot more decision making to the process. Low health, high suppression marines might not be the best unit to lead suppression with, after all!

Active suppression systems also work well with a lot of units crammed into small, line-of-sight breaking level layouts. Steam Marines 2 does not have the destructible environments of its predecessor and this makes choke points like hallways and doors deadly. Leapfrogging by advancing, suppressing, and repeating is preserved from a traditional cover system except you don’t have to rely on the environment cooperating with you.


We can’t see shit, sir.

Overwatch, or any mechanic that allows interruption or interaction for a side when it’s not their turn, provides for both varied gameplay and tension. If I send a marine through that tile is he going to get cut to shreds? This is largely an information war more than anything else for two reasons:

  1. The opposition has to know about your plans in order to avoid/counter it.
  2. You have to have a hunch that reaction is more beneficial than a similar action performed on your turn.

The problem with Overwatch, or Guard Mode as it’s called in Steam Marines, is that it’s frequently a “default” action. It’s just something you do when you don’t know what else to do. It’s a safe action. As with cover and turtling, I prefer to dig that out of my systems.

The other appeal of an Overwatch mechanic is that, in a traditional cover system, you don’t have to really move around much. Again, it’s playing it safe. As mentioned above in the cover section Steam Marines 2 has an auto-engage target. Whenever a unit attacks or suppresses another unit, the defending gets to attack the attacking unit – order depends on circumstance.

This makes attacking similar to defending. You need to suppress and move to good positions and you (should) suppress and attack targets to avoid effective retaliation. There are pros and cons to this. Pros include a depth of tactical decision making and much more active turns.

A rather large con includes the potential for “samey” feel turns, where you suppress, move, attack, repeat. This is, on its face, only marginally different from move to cover, attack, repeat. The main difference from that gameplay level is the micro decision is who suppresses whom as opposed to who moves to what cover. It is arguable that the traditional cover micro decision is superior because it can be made hastily, without too much thought, and be reasonably effective. Whereas picking bad suppression targets can really doom you in a suppression/retaliation system (given a high enough damage-to-average-unit-health circumstance).

Therefore Guard Mode in Steam Marines 2 provides a very different mechanic from the first game. Instead of acting as an Overwatch marines in Guard Mode have increased accuracy, damage, and initiative when retaliating against attacks but not suppression. The key difference is the positional play element – you actually want to push marines forward and place them in Guard Mode.


Wait, what about turtling?

You don’t actually want to turtle with Guard Mode because enemy units can dogpile suppression and then rip your marines apart individually. You need to be actively taking them apart with both your rear and forward units rapidly otherwise you’ll lose due to attrition.

It gets particularly hairy when you factor in that attacking/suppression/Guard Mode are now in their own resource pool and no longer related to action/movement points. A unit with two attacks per turn who can attack then suppress or suppress then enter Guard Mode is a very different beast from a unit with only one attack per turn!

It’s not quite a weapon triangle, but it can help to (sort of) order it in that kind of cyclical fashion:

  • Guard Mode > Attack
  • Attack > Suppression (on non-attacker)
  • Suppression + Attack > Guard Mode

Or, combined:

  • Suppression + Attack > Guard Mode > Attack > Suppression (on non-attacker)

Simple, right? Right?


Of course, the effectiveness of such a suppression/Guard Mode system is highly dependent on the numerical balance of the game with regards to weapon accuracy, range, damage, armor and health on units, et cetera. So far the results are promising and I hope to keep refining the current system.


Thanks for reading,
Mister Bums

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