I currently develop my codebase serverside in Java (SmartFoxServer 2X). SFS will likely be the best multiplayer Java socket server for the next couple decades at least.

Clientside I develop my games in AS3/+Adobe Air + Java (jPCT). The reason is... Converting AS3 > Java, or Java > AS3 is basically just a copy/paste with slight syntax changes which you can easily mostly automate with a simple script.

I am only concerned with targeting Windows/Linux/Android. I am only starting to become interested in a HTML5 port, but the performance is still horrible. I only develop games which consistently perform at 30FPS or 60FPS for at least eight year old hardware. WebAssembly will most likely fail because of security flaws.

I am considering converting one of my games to C++, but I am having trouble finding a game engine which will perform much better than jPCT or Flash>Adobe Air Stage3D. Trying to find a optimized open source OpenGL GPU accelerated C++ 2D engine with transparency, blend modes, and not looking to do the low level OpenGL programming myself. A simple game engine like this should only be around 15,000 lines of code at most. The major problem with Java, Flash, and HTML5 is garbage collection. It causes issues with creating a game which plays very smooth at high framerates.

Looking for something which can be optimized to render 5,000-8,000 small sprites on screen with transparency at 60FPS on upto six year old hardware at a resolution of at least 1000x800. Anyone got any ideas?