Bereaver

We go from one of the weakest bots in the SSCAIT to one of the strongest. Bereaver has by far the most impressive rise to power of any bot, having shot to the top position of the SSCAIT ladder within days of its first game on the 30th of September 2016.

Bereaver’s name seems rather appropriate. It certainly caused significant bereavement as it took the top ladder positions away from the likes of Krasi0 and Iron, and the name also acts as a pun of one of Bereaver’s best used units: the reaver.

Bereaver’s play in many ways resembles that of ZerGreen bot, which was added to the SSCAI ladder only a week before, but with stronger macro, and much better micro of gateway units (and unfortunately no funny BM).

As of the time of writing, Bereaver is in second place in the SSCAIT round-robin, just behind Letabot (Martin Rooijackers).

Strategy:
Bereaver is a strategically very versatile and adaptable bot. It typically begins with a few zealots, then transitions into dragoons as quickly as possible, then builds reavers and high templar when it is safe for it to do so. It buys upgrades such as dragoon range and attack at generally sensible times. For very late game (usually when it maxes out) it transitions into carriers.

Against rush bots, such as ZZZKbot, Bereaver pulls 6 probes to its ramp to block it. While the timing of this pull is often a little off on certain maps, leading to unnecessarily lost mining time, the probes are usually enough to fend off early zerglings, workers and/or zealots until it makes enough units of its own.

This behaviour is determined by scouting information, rather than hard-coded counters for specific opponents, which has both advantages and disadvantages. It means that bots which are altered to play new builds against certain opponents can still be countered, but it means that Bereaver can make strategic errors if its scouting is denied, as Jay Scott reported on his blog that his own bot (Steamhammer) was able to do. Using heuristic based counters rather than hard-coded counters are also often more useful from an AI research perspective, as discussed in one of my other posts.

Macro:
Bereaver is able to take additional bases, and usually builds photon cannons to help defend them. Its playstyle generally seems to be very defensive when it comes to macro, and it often waits a little too long before taking additional bases, but rarely has problems with getting the bases down, and loses them even more rarely.

Its spending of resources seems slightly weaker than that of most other strong bots, and it will occasionally float a few thousand minerals while still not maxed out. Building additional gateways or robotics facilities and pylons, or simply taking expansions sooner when this happens could help turn this already very powerful bot into an unstoppable one.

Taking bases when it’s not necessarily safe to do so is a risk, but not a significant one when you’ve got minerals to spare – the worst result is effectively equivalent to losing a probe, as the minerals wouldn’t be of more use stagnating for several minutes in Bereaver’s bank than they would going into a building that gets destroyed. On the other hand, the potential benefit of securing another base is significant, as it provides map control, and (in most cases) an extra source of vespene gas, which could help balance the mineral-heavy economy. Cannons, army positioning, or just retreating the probes back to the mineral line of another base would help prevent probe losses, should a risky expansion be attacked after probes have been transferred – anyway, when floating minerals and with 3-4 saturated bases, losing 1 mineral line isn’t the biggest loss. The macro is by no means weak, but it is probably the weakest of Bereaver’s attributes.

Micro:
Bereaver’s dragoon micro is very strong. Unlike most other protoss bots, it tends to split up its dragoons when they are approached by enemies and have them all kite separately. This spreading makes it extremely difficult for melee or short-ranged units to chase down more than one or two dragoons at a time, prevents the dragoons taking splash damage from tanks and reavers, and means that dragoons with full shields can tank for ones which have taken damage. When there are no enemy units present, the dragoons move together in a group to ensure that they have strength in numbers when they next encounter a threat.

Reavers, as previously mentioned, are also well used. Scarabs are intelligently targeted into groups of units to maximise damage, and the shuttle drop micro is also very effective. Shuttle positioning still needs a little work, as they will often be moved over marines or other anti-air units and shot down, especially while defending, but the drops and pickups themselves are pretty much frame-perfect (though this isn’t really that difficult for an AI).

Most other units are also well used. Storm targeting is quite good, as is zealot positioning, but these are less significant as templar and zealots aren’t usually built in large numbers. I’ve not seen much stargate play from Bereaver other than an occasional corsair used for scouting, so unfortunately I can’t really comment on that.

If you’ve got any of your own ideas or comments about this bot, feel free to post them below. If you’ve got any questions about this bot, I’ll try my best to answer them (though it’s likely I’ll have no idea what the answer is). If Damir Akhmetzyanov comes around here, hi, I hope that my comments are helpful, or at least interesting.

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