Train (de_train) is a small but open-spaced map that allows snipers to easily eliminate exposed enemy players and makes designing a quiet and controlled ambush harder to implement. Due to the narrow passageways and the simplicity of the map, combat between the Terrorists and the Counter-Terrorists is very fierce in the bombsites, back/long halls, and occasionally, the back alley and the CT spawn zone.
Although it is tempting for players of both teams to head over to Bombsite B (as it is nearby the spawn zones for both the Terrorists and the Counter-Terrorists), the back and the long halls can contain other players who do not want to be involved in the first minute of outside combat. There is also a ladder in the hallways that will allow the Terrorists to reach Bombsite B from behind the CTs thus any wary player should keep an eye on this section and the entrances.
If fighting does not occur at all or some of the players were not encountered in these areas, then it is likely that the back alley or the CT spawn zone may contain a few players who have arranged an ambush or are simply waiting for the right time to move.
Notably, it is possible for campers to hide underneath the derailed train cars and either launch surprise attacks or wait to plant/defuse the bomb.
Combat does not occur in this area of the map unless the Terrorists have decided to reach this area by using the back and the long halls to avoid confrontation in bombsite B. For many players in the Counter-Strike Community, both bombsites are structurally very similar although Site A is less open-spaced, has a wide overlook area that gives players an advantage over others in the lower sections, contains less light, and does not have a roof. Generally, players will choose this bombsite for ambush purposes (as a Counter-Terrorist) or to plant the bomb (as a Terrorist) if they lack the proper weapons and equipment to engage enemies head-on.
If the bomb is planted in bombsite A, snipers can be seen at the upper areas, above or even underneath the train cars and will be aiming their weapons at the entrances for enemies to rush into. Players will counter this by throwing smoke grenade and flashbangs at these entryways for concealing movement and quickly eliminate blinded enemies. However, some survivors may be hiding under the train cars and will not fire their weapons until an enemy player gets too close. When this happens, inexperienced players may not be able to trace the source of the gunfire, in the dark area, until it is too late for them to properly react. Prominently, veteran players will throw an HE grenade at the train cars to inflict heavy damage on enemies as they cannot escape easily while they are crouching.
Finally, if you have to rush into this bombsite, try to throw a flashbang or a smoke grenade at one of the entrances to distract the enemy. Next, try to silently enter into another entry point and eliminate targets from behind or plant/defuse the bomb (although it is better to wait until all the enemy players have left their positions or were eliminated).
Bombsite B/Roof/Side Alley:
While Bombsite B and A do contain similar aspects, site B has a roof that allows a sniper to overlook the entire area and the bomb target is inside an enclosed loading dock (in Global Offensive, this was changed as the target is now located from the very center of the bombsite). Depending the amount of successful rounds the Terrorists or the Counter-Terrorists have, the winning/dominating team will rush into this bombsite unlike the losing team.
Since Site A has more daylight, be sure to avoid crouching and crawling under the train cars as it will greatly reduce your speed and allow enemy players to eliminate you easily. Instead, either simply crouch and shoot at the legs of your intended targets or try to get to the top of the train cars as it offers less exposure (unless there is an enemy sniper at the roof).
Grenades can be throw above the train cars to disorientate aggressive players. However, it is possible to throw a flashbang or an HE grenade through the bottom of the train cars to increase the effectivemess and range. Meanwhile, smoke grenades are better used to conceal your current position or for distractions.
In both bombsites, it is crucial to plan ahead (and devise a backup plan!) before moving through the areas with the train cars. In just about every angle, exposure from enemy fire will lead you to being pinned down or even eliminated without giving you room to counter-attack. Just in case, it may be best to wait, not rush, when it is required to enter through the bombsites.
There are three ways in traversing through the bombsites: you can either simply walk around the train cars, crawl underneath the train cars, or climb up the ladders and take down enemies from below. As a precaution, be sure that you have fast reflexes as it may be able to offer enough time to either attack or retreat from aggressive assailants.
As for the roof, a sniper can take advantage of this spot and have a good look of the entrances to the bombsite. In Counter-Strike 1.6, be warned that assailants will keep an eye on the roof for enemy players, as that spot offers no cover from bullets. In Source games, the air conditioner can be used for small cover from bullets. Enemies will either fire their weapons or throw a grenade at you to force a retreat.
The side alley can contain some campers thus players will either avoid this area or throw a flashbang before entering the area. Nevertheless, it is very hard to predict exactly when the enemy will rush into the side alley so players will prefer to set up a distraction and find more suitable tactics to enter bombsite B.
Back Hall/Long Hall/Ladder:
If enemy players are not encountered in the bombsites and the back alley, then these areas will have some combat. Due to the narrow passageways, multiple groups of players may struggle to proceed through this area. Unlike most other areas in Train, the hallways and the ladder is very suitable for ambushes as intended victims will not have enough time to escape from assaulting assailants.
It is here that close-ranged weaponry are the most effective weapons to use although a sniper can be found among other players. Primarily, the XM1014 auto-shotgun is deadly in the enclosed areas while players can be pinned down in the back hall, if an AWP user is above the long hall.
Grenades and ambushes are highly effective and should not be underestimated in this situation. To be sure, always throw a flashbang before entering the area, especially when attempting to descend/ascend through the ladder. Sometimes, a camper may be hiding behind the crates in the back hall or below/above the ladder.
CT/T Spawn Zones/Back Alley:
Fighting will only happen in the situations when there are inexperienced newcomers who prefer to wait until the right to move into combat or when players decide to camp in their respective spawn zones, if they do not have enough money to purchase preferred weapons and equipment.
Generally, the back alley connects between the Terrorist spawn zone and bombsite B thus mainly serving as a path for players who need to access to Site B. Once in a while, however, some members of the Terrorist team may not want to rush into the back halls or the bombsite and will wait in their spawn zone or the back alley. This allows the CTs to barge through the area and trap the enemy (if they have enough firepower and present team members).
Instead of being a hot combat zone, it mainly serves as a shortcut or even an alternative sniper nest between the bombsites. Due to this, players will heavily watch or camp nearby the entrances of this area.
As a result, players who rush through this area, especially when the bomb has been planted, will quickly be eliminated by a barrage of bullets from the enemy.
Despite the disadvantages, it is possible for players to hide in the middle and somehow ambush players who were not careful.