Kermielovah, remember "Toy Story 2." Toys and games are meant to be played with. Do you really want to look back on all those "fond years" of staring at a box you couldn't open? And whether or not something will become valuable is always impossible to gauge. I have a bunch of Star Wars figures that I bought and never opened, figuring their value would skyrocket. They're worth maybe a couple of dollars more than when I bought them. Do you want to deprive yourself of playing the game for something that might only increase slightly in value?
I'm not picking on you. I'm just saying: open your game and have fun.
If you're really that interested in trying to make money off of it at some point in the future, ask another relative to buy you the same game, and you can keep that one preserved for all time.
Hope that helps. Happy playing, and let us know what you think of it!