Compact but fairly strong Reversi program. Lite version (with Ad) has only one level, but it would be strong enough (or too strong) for most players. Once finished, game can be played back, and computer shows his thought on the moves you made. Paid upgrade will add more stronger levels. - Level 5 uses Richard Derome's Edax engine with further optimization in native code. Edax Level is adjustable in Settings. Edax is licensed under GPL3. Source code is available on https://github.com/okuhara/edax-reversi-AVX. - Level 4 and 5 uses the Unified Book 2010, assembled from several strong opening books on the internet. See http://www.amy.hi-ho.ne.jp/okuhara/edax.htm (in Japanese) for details.