YouTuber Marbozir, an experienced XCOM 2 player, faces a tough situation on a heavy-activity black site mission. Topics from the highlights below include the importance of mobility, avoiding fair fights, taking necessary risks, asymmetry in risk evaluation, and target prioritization.
Most of the clips here come from the early stages of a single difficult combat, but we start a point raised earlier in the video. Space and time can be thought of as spacetime, a real life physics concept that is also fundamental to gameplay. Every game has time, space, and movement in some form, and spacetime dis/advantage in its various forms (incl. speed, positioning, territory) is highly impactful. Here, Ryan's poor mobility is potentially problematic. With one soldier slower than the rest, Marbozir has two choices. The first option is to voluntarily pass up on using some of his XCOMs' mobility and keep the squad grouped, or he can allow faster squadmembers to range ahead but dangerously stringing out his team:
Now to the dangerous fight. Marbozir's goal is to only face a single pod at a time (if possible), raising a tactical theme is almost too obvious to mention were it not so important and omnipresent. By picking one-sided fights over more closely-matched ones, a player reduces resource expenditure and risk. For example, this Dominions 4 post from a couple of weeks ago highlighted the importance of one-sided first strikes in reducing the enemy's ability to inflict losses. A similar idea indirectly appeared in an Age of Empires 2 test of various compositions of jaguar warriors and Teutonic knights against one another. Even seemingly-small increases in advantage can spiral, as each fallen foe reduces incoming damage such that each subsequent enemy falls ever more efficiently. Here Marbozir has successfully guided his squad undetected through most of the map. The objective is in sight and guarded by a stationary group. A moving XCOM soldier spots a patrol squad across the room. Since the XCOMs are still undetected, Marbs waits hidden for the patrol to move, hopefully away:
The alien turn does not go favorably for Marbs. A previously-unseen patrol comes from behind. Compounding the problem, the patrol across the room does not move away helpfully but instead comes closer! "This will completely mess up my plan," Marbs laments:
Marbozir cannot do much to stop the flankers from spotting him through the windows, but can send a soldier to close the open door. It's a risk, as the enemies in the fog may spot the door-closer. The move works, and Marbozir fades another turn unspotted:
With the patrols ahead and behind breathing down his neck, Marbozir nervously waits on overwatch again instead of firing his rocket lanucher at a close-packed group. To understand the decision to wait, it is important to know that XCOM enemies never attack on the same turn they spot the player's squad. Opening fire with the rocket launcher would end concealment on the XCOM squad's turn, leaving the aliens their full turn of awareness in which to shoot back. Waiting quietly on overwatch leaves a chance of staying unseen. Even if spotted by patrols on the alien turn, the enemy will take cover but not yet shoot. The overwatching soldiers would take reaction shots and then receive their normal turn. Fortunately for Marbozir, the patrols move away enough that, at least to start, he will only have to fight two groups at once and not three:
What is the best way to start this combat? Marbozir's first inclination was to begin with the rocket launcher against the tightly-packed patrol group. However, as they say in chess, "when you see a good move, look for a better one." Marbs hits on a plan with even better value. Iron curtain is a gunner ability from a the Long War Perk Pack mod that deals AoE damage in a cone and inflicts a 2-turn movement-reducing debuff. Opening with iron curtain will trigger the two groups in the room, causing them to seek cover. Only after the triggered groups move to cover will Marbs fire the rocket to destroy cover in an area, leaving some aliens exposed:
Another type of enemy to focus is one that buffs other units to multiplicatively increase the danger represented by an encounter. Aliens with explosives fall into this category, as their efficacy lies more in their ability to destroy cover than in the guaranteed damage of explosives. Here, the elite shield bearer's buff must be stopped. It has 12 health left, and is providing itself and two other units with five points of shield each. The successful instant Skullmine kill on the shield bearer effectively deals 37 total points of damage:
When the berserker group appeared behind, it looked like the XCOM squad was doomed to die, but careful decision making in a scary situation let Marbozir's squad accomplish the objectives without losing a single soldier. Good positioning and efficient use of turns harnessed as much spacetime advantage as possible, most especially waiting to face only 2 squads at once and then taking time to find the best line of play for the opening volley.