Here is a good reply from a poster on another forum:
I think games feel amateurish when they are unpolished and without a sense of style. I have seen many professional games that feel amateur to me, but usually it is indie games that are really bad about it.
Here are some of the signs that I see as amateurish:
- Obvious typos and misspellings
- Inconsistent graphical style, such as photorealistic backgrounds and cartoon characters (though this style can work, most indies don't make it work)
- Unpolished UI, especially in the transitions from screen to screen
- Clunky controls with poor animation
- A poor 3D engine used when a great 2D engine would have been better
- Overuse of certain "humorous" elements : Pirates, Ninjas, Robots, Monkeys, etc... (though some games hit these dead-on... Earthworm Jim)
- Music that does not fit with the gameplay and presentation style
- Poorly chosen, improperly mixed sound effects
- Superfluous gameplay elements (such as a jump button that is useless throughout the game... Doom 3 anyone?)
- A system that was obviously scaled back, such as a hugely complex magic system but only seven spells.
- Misaligned textures in the levels
- Generic level designs, lack of scripts/triggers/events within the levels
- Trying to jimmy a generic backstory into a game that didn't need one (how does fighting the Robot of Doom equate with making a toothpick statue?)
- Focusing so much on a poorly written story that the rest of the game suffers (most indie RPGs fall into this category, written by people who want to write stories, but like to play games)
There are many more tell-tale signs, but basically the lack of polish and an obvious misunderstanding of what makes a game great are the signs that I see. Generally, I think the problem is that indies often want to compete with the big-guns of gaming. This means that they bite off more than they can chew and then don't have the time to give the game that extra polish.
Kori