Snowbase is a map designed for Team Fortress 2's Attack/Defend mode, where one team attempts to capture a series of control points while the other team tries to stop them.
The map is divided into two stages, each with two control points. The first stage starts in a small fishing village at the base of a mountain, and leads into an underground facility with an elevator leading up the mountain. The second stage starts at the top of the elevator, leading around a cliff to a helipad and ending in a spy movie-inspired secret base. This progression aims to fulfill the fantasy of invading a secret base, which also matches the difficulty the attacking team has in pushing into enemy territory.
I was responsible for the full layout and artpass of the map from start to finish, as well as continued layout updates based on player feedback in the years following the map's original full release. The spy base portion of the map is inspired by and uses assets by Lauren 'Yrrzy' Godfrey, and also uses bespoke art assets created by Sebastian Grus.
Steam Workshop page
Snowbase was originally drafted and tested in layout phase as two separate maps, which were stitched together and tested as one map later in development. This made it much easier to iterate on each stage and get more focused playtest data and feedback.
One significant lesson learned through the development of this map was in balancing multiple stages together. While testing the stages individually, the second stage had an attacker win rate of around 50%, while the first stage had a win rate around 70%. After artpassing and combining the two stages, the first stage win rate dropped dramatically for reasons that are still unknown to me. This had a knock-on effect of significantly increasing the win rate of the second stage. Re-balancing efforts were focused on the first stage, as a high win rate on the second stage was merely a symptom of the first stage weeding out most attacking teams that would fail on the second stage.
The first point of the first stage was originally a raised platform with a passage underneath. This design proved to be a bit awkward with regards to sightline management and providing obvious locations for engineer sentry placement, so it was replaced with a shed that provides an obvious anchor for defense and better controls sightlines. Both teams can easily access the roof of the shed via stairs or a mound of snow (hidden behind shed in image), which functions as a highly exposed yet very powerful area to control.
The final point of the second stage is the elevator that takes the attacking team up the mountain. Originally the point was on the elevator itself, but it proved awkward and unintuitive for player navigation. This design also proved to have very volatile balance, with attacking either being too easy or too difficult depending on how well each team knew the layout. The current version moves the control point to the bridge, which is a more obvious and central position in the room. The elevator functions as a high ground flank that both teams want to control.
The entire room was also rotated 90 degrees to make the flank more quickly accessible to the attacking team. This broke the continuity between stages of the elevator, but most players do not notice. I briefly experimented with rotating the entire mountain to match, but it wasn't worth the effort and looked worse.
The first point of the second stage is a helipad. In the original design, the helipad is surrounded by a large deathpit. In a later version, a significant amount of ground was added around the helipad, giving players many more options on how to attack or defend the point. A far high ground flank was added to give defense a good sniper nest and a place for offense to outrange engineer sentry nests.
In the original design for the final point of the second stage, a small wall of waist-high computers provides cover to an otherwise completely open capture area. This was replaced with a tall computer that provides more consistent cover and allows players of both teams to engage in the battle at close range. Allowing offense and defense to contest the capture area while in cover makes starting a capture easy, but finishing one difficult, leading to intense battles where both teams feel like they just barely won or lost.
In older versions of the map, a tight flank was provided for the attacking team to access far ends of the main room, but that tightness made it very hard to push against a competent defense, and the layout had no room for expansion. The entire final room was mirrored to give the flank more room to breathe, and to make it so a defensive push through the flank would not exit behind where the attacking team tends to gather for pushing the point.