As a developer, there will be times that you will need to pitch a game to a group of producers, investors, peers, etc. Over the past few days I've watched quite a few pitches from my peers for various games without a variety of results. Frankly there are many things that you should be thinking about in this situation to help make your pitch a success. A presentation of some kind helps, games are a visual medium so your presentation should be visual as well. Yet you could get by without one, though I would certainly say it's not recommended. You could have a working prototype of your game that you put together from pre-existing material so people could potentially play the game to get an idea before hand. Once again though, it's extremely helpful but not always an entirely possible route to take. There is though one thing that I would say is absolutely indispensable when you are pitching a new game: excitement.
BE EXCITED! I get it, presentations can be difficult. In truth though it's something that you're going to get used to, because as a developer your work is always on display. I actually think that giving a presentation can be pretty exciting because it is a chance to show off what you've been doing. Personal feelings aside though, here's the most basic crux of the issue: if you don't seem to care about your game then why should I or anyone else for that matter? If you sound like the emotional equivalent of watching paint dry when you're presenting your game, then I can assure you that listening to it is just as interesting.
Wait, wait, wait... we're getting to the good part.
Perhaps it's just presentations nerves getting the best of you, though chances are if it's just nerves then you should sound understandably nervous. If you feel bored while you're explaining your game then you should really take a long hard look at your game. Why did you even think it was a good idea in the first place? If you can remember the reason (and it's a pretty bad sign if you can't) then what happened that caused your passion for that project to leave you? If it really is just presentation nerves then you need to practice your pitch whenever you get the chance. Ideally you should do it in front of some other people just so you can get used to being in front of people. No matter what happens though you need to remember to be excited about it and if you can't be excited about it then you need to figure out why you're presenting it. People can and will read into the emotional content of your speech and at the end of the day if you want other people to play your game then it at least needs to sound like you're excited to play your game.