I’m looking to build a test server that allows an old client of a video game in unreal engine 2.5 to successfully reach the in-game lobby (including full login with username/password). The goal is to reproduce the exact handshake and packet sequence the client expects, identify the validation that causes the client to close the connection, and adapt the stub (or apply a temporary hook) so the client completes the login flow and enters the lobby in our test environment. What we already have: The client runs standalone (launcher dependency removed). Several Python stubs for testing (modes: hello-only; hello→blob; 8-byte hello; hello + delayed second packet; passive receive-only stub). Network captures (PCAP/PCAPNG) and TCP stream hex exports showing the observed handshake (08 00 43 01 from client → 08 00 43 02 from stub → large blob 05 DC 43 03 ... that currently triggers a close). Partial memdumps and binary dumps of the recv buffer (example base ~0x18B10008, observed length 0x05DC) and a small dump showing BAADF00D markers. Debug artifacts: register dumps, stack traces, disassembly snippets and a modules list indicating offsets in chaoschannelclient.dll (recv wrapper, enqueue, EIP in recv handling, closesocket caller, and the comparison that triggers close). Extracted PDBs for the client and several partial .txt dumps for context. Full PCAPs and PDBs can be provided under NDA. Expected deliverable: an adjusted stub or a temporary, well-documented intervention that enables the client to accept credentials (username/password), complete login, and reach the lobby; plus a short report listing the relevant offsets, functions, and reproducible steps.