Red Sky Battle is an attempt by creators Pro Igork and ALEX_230_VOLT to extend and finish "Wrath of Shredder", a long abandoned TMNT fan project originally conceived by BonusJZ.
Per the creators:
Sadly, this development appears halted as well, and like BonusJZ the status of Pro Igork and ALEX_230_VOLT are unknown. However, despite technically being an abandoned demo, Red Sky Battle is fully playable and features an impressive level of detail, polish, and techniques. It is well worth a play-through and makes a fine addition to any TMNT fan's collection.