Real-time & distributed
Matchmaking queues, room-based sessions and live move sync on Socket.IO, with Redis
Pub/Sub keeping game state coherent across server instances so the thing scales sideways instead of up.
Transport & cryptography
WebRTC DataChannels with chunked streaming, flow control, AES-GCM end-to-end encryption
and resumable transfers verified by SHA-256 — files that never touch a server.
Search & optimisation
BFS, DFS, IDDFS with pruning and finally Korf's IDA* over three pattern databases,
solving any scramble up to 13 moves optimally. Written in C++ with compact state representations.
Product surface
JWT and custom OAuth flows, resource-level authorization, centralized request logging,
admin analytics, indexed full-text search and PDF export — the unglamorous parts that decide whether
software survives contact with users.