This release has killer moves and PVS. Elo increase in self-play is +81, +/- 20 Elo. I'm satisfied if this version achieves +50 or +60 in the CCLR Blitz list over Alpha 2. Thanks in advance for the tests for the CCRL listThis release adds two new features: Killer Moves and Principal Variation Search. In self-play against the previous version Alpha 2, this new version is about +80 Elo (+/- 20 Elo) stronger. Since Alpha 3.0.0, a pre-compiled binary for MacOS (Intel) is also available.
New features:
- Killer Moves
- Principal Variation Search (PVS)
Changes:
- Switch versioning scheme to SemVer. Versions are going to be in the
form "a.b.c" from now on, with the following meaning:
- Increment **a**: A new strength-gaining feature was added.
- Increment **b**: A bug was fixed that gained strength.
- Increment **c**: A feature was added or a bug was fixed that did not
gain stregnth. It is not necessary to test such a version for a rating
change.
Misc:
- Updated crossbeam-channel to version 0.5.1
- A Makefile was added, so Rustic can be built using "GNU Make". When
typing "make" (or "gmake" in MacOS), the Makefile will build all Rustic
versions for the platform it's being compiled on.
- Re-add showing the size of the TT and number of threads in About.
- Fairly large update of the book on https://rustic-chess.org/.

I also implemented and tested Aspiration Windows and History Heuristic, but they didn't gain any strength so I took them out again. I'll try again after the evaluation has improved in version 4.0.0.
The engine now has a Makefile. Just typing "make" (or "gmake" on MacOS, after you install GNU make through Homebrew) should be enough to build all Rustic CPU versions for your platform, assuming your development environment is installed correctly. The rest of the updates are the documentation for building Rustic (build.md), and the book/tutorial at https://rustic-chess.org.
The next version is going to be more exciting from a chess playing point of view. That will be the one with a tapered and tuned evaluation. I hope to hit at least 2100 with that version, and at if so, it will be Rustic 4.0.0, finally out of the "alpha" stage.