Lack of motivation can be for many reasons...
1) You burnt yourself out. Take some time out for regular exercise.
2) You're comparing your solo effort to something like COD, WarCraft, Metroid, GTA or whatever. Realise now that 95% of all games made are done by a team of people which can range from two to two hundred. The resources, coding etc requires many to pull together...
3) You just don't know where to start! Seriously, either read a book on Software Development(Engineering) or take a course in it. Interaction Design is recommended as a companion subject. Also, if you want to improve in an area - take some time out to learn it. Whether its drawing, animation, maths, AI...whatever...just do it. You may end up sucking bad at something, but at least you'll come away with respect for it and be able to bare in mind the associated complications. That's useful because it allows you to communicate better with another team mate because you respect their problems.
4) Get used to developing editors. One really does need tools to build something! From Object to level editors - make it happen!
5) You feel you have to be excellent at everything. Not so! You don't need music, sound or FMV intros. Also, not every game needs an epic story to rival The Bible. Your animation for a game does not need to rival the old men of Disney, nor does your music have to put Vangelis to shame...if you must have all these things then add them with functionality in mind.
6) Your only inspiration is modern monster budget games. You know, there was a time when a single person could write their own game without assistance. At best, teams ranged from one to a dozen staff members but there was plenty of lone wolves. Take a look back into the past - as in the 1980s and early 1990s. On resource limited machines such as the C64, Spectrum, BBC Micro, Amstrad etc...that is an era to look at as it shows you what a game really is at its core because developers back then could barely afford programming power to display a single sprite on the screen, let alone lavish FMV, sound, bells & whistles...it simply wasn't going to happen on a pathetic 48K of memory! But bugger my boots, miracles did happen!
Edited by Anri, 09 February 2013 - 05:15 PM.