Part one of an ongoing saga, Titan has some of the best usage of the HL2 engine I have ever seen - bar none. From dust particles to stellar lighting and texturing to subtitle display, your only indication of the engine in use is the unfortunate inclusion of the HL2 facial models and sound effects that are all too familiar. There are also some derailing usage of objects that pull you from immersion such as banging your wrench on an object to "fix" it. It's either engine or author shortcoming but it hurts the otherwise fantastic package.
While it's not terribly long and the voice talent is the standard indie-rific, the gameplay and the journey are great and I look forward to the next instalment.