Arise, arise! Fighters of Terpentin! Lane-pushing games are best known as 5v5 matchups, but over the years there have been plenty of maps trying out different configurations.
Terpentin is one of the better-executed 3v3v3 maps: consisting of three AI teams, with 3 player-controlled heroes on each. While nothing special in terms of graphics or hero design, its offers a large variety of map objectives, which are tricky to prioritise.
As usual for 3v3v3, the bases are arranged in a triangle. There are four lanes coming out of each base, two towards each opposing base, along the sides of the triangle. At best, a team can never have a hero in every lane, so there is always an element of choice regarding where to be.
(Many 3v3v3 maps have a 'mid' lane from each base to the centre of the triangle. This usually ends up being a mess, because no one team can push against the other two, eliminating any meaningful strategy, and the surplus of experience means every player wants to be there. I'm glad Terpentin avoided this.)
Every hero starts with an ability allowing them to Teleport to any allied building. It's quick to cast, and provides immunity to most spells (but not attacks) while casting. The two-minute cooldown is comparatively long though, for a game where you always have at least 1 empty lane that might need defending.
One of the most striking features of Terpentin is that there are a lot of possible resource streams, many of which are contestable. The most straightforward is to grab last-hits on one of your four lanes, but a daring player could head to one of the lanes on the opposite side of the map, where there are no friendly troops, and consequently twice as much experience and gold to be had. This is risky because you're exposed with no tower to run under, but has the potential for double gold and experience.
The central 'inner triangle' of the map is the most accessible location to all three teams, and contains more contestable resources, such as the Whisp Altars. While under the control of a team, the altars grant a passive gold per second boost to every hero on the team. Taking control requires that all three of a team's heroes to be standing on different altars at the same time. A well-coordinated team should be able to pull this off quickly while the enemy players are distracted, but it requires committing all three heroes to an attempt.
Wood is a secondary resource in Terpentin. It is only available by killing the creep camps in the center of the map, and can only be spent to hire permanent player-controlled Mercenaries. The mercs include a light melee unit, a heavy melee meatshield, and a siege unit which can attack enemy buildings from a long range. These can be useful to help secure the map's other objectives, such as guarding your team's assets or making space for your heroes to move around.
The creep camps are tough at early levels. Each camp has 3 creeps, and each creep rewards a modest sum of gold plus 1 wood when killed. The creeps respawn individually 45 seconds after their death, which makes them practical if you only need 1 wood, but impractical to try and 'block' the camp from respawning by leaving only one alive.
Two other sources of passive gold gain are each team's Magicly Cove, a building which grants gold per second to each of the team's heroes simply by being alive. The coves are located outside each team's base and are only protected by a single tower, so enemy teams can attempt a raid to deny their opponents' income, or make the enemy waste teleports.
Each team also has an Outpost building, which periodically spawns a worker to bring gold to the team's main base. Upon reaching the main base, the gold is 'delivered' and team's heroes get paid, but it's possible to intercept them and take the gold for yourself. In practice, the workers aren't frequent or valuable enough to put any effort into stopping, and as the outposts are only a short walk outside a team's base, the only time you'll kill these is during a siege.
Finally, each team also has a Vault. Every 75 seconds, some gold coins are added to the vault, and every 50 seconds the vault door opens for 10 seconds (it will also open if a unit inside tries to exit). While it's not worth making a vault trip every minute, eventually enough of a fortune accumulates to warrant stopping by. Watch out though, because the vaults are undefended, so anyone can sneak inside and steal the loot!
The game's items include a selection of the basics, with some recipes to combine effects and save on item slots. The centre shop boasts a few powerful recipes, as does the wandering merchant who makes his way from base to base.
One of the minor shops stocks the usual selection of Warcraft's potions, including temporary invisibility, invulnerability, and instant heals. An addition to the usual selection is an item which can repair towers by a fixed amount of life.
Aside from items and mercs, players can also permanently increase the number of troops which spawn on their lanes. Each lane's troops are increased individually, so players must decide whether to invest heavily in one lane, or spread their efforts across several. It takes a while before the increased numbers take effect, so don't wait until the enemy has +4 on a lane before starting to react!
Players can also buy upgrades for their team, which improve maximum life, damage, or armour. They can also invest in tower upgrades, improving maximum life or damage. Being able to choose between towers and units is nice, as many maps offer lots of troop upgrades, but none that present any meaningful choice.
Each entrance to each team's base is overlooked by a single Command Tower, which does nothing on its own, but may be upgraded a single time to a more powerful defensive instalment. The upgrade requires a nearby hero to initiate, and takes 90 seconds to complete.
None of the other towers in the game behave this way, so it's a bit of an anomaly. The thinking seems to be that if you are wary of a big push in advance you can pay to bolster your defences on that lane, but if the enemy takes you by surprise, they can take out the command tower while it's still unarmed. It's an interesting feature, but is of greatest benefit to the teams who are already winning.
Terpentin plays really well into the uncertainty of a 3v3v3 matchup by having lots of ways to mess with your opponents' economy, or focus your efforts against a particular team. Coordinated players can accomplish all kinds of objectives, but it's impossible to cover all your openings with only 3 heroes against 6, so there's plenty of room for betrayals and opportunists.
Ultimately victory is decided by who has the stronger troops, so finding a balance between making money, spending money, and interfering with your opponents' plans makes for an engaging challenge.