"Pokemon Go" is a revolutionary game in more ways than one: it's the first game to populate the real world with video game characters that's actually in the mainstream, and it's probably also the first game that's successful in getting people to go out into the outside world in doing so. No other game has really done that, mobile or otherwise, as the game's design has put a whole new meaning to "play anywhere."
However, sometimes you just don't want to go out of your house even though you still want to play "Pokemon Go." Yes, it's possible. There are a few tricks that allow this, but they're either expensive or dangerous (in the sense that developer Niantic Labs can discover your cheating and ban you from the game, which is already happening to GPS and bot hackers who level up too quickly).
First of all, here's a really safe and legal tip: sometimes, GPS is wonky in such a way that the satellites that triangulate your position can be inaccurate and place you in different, slightly distant spots in a short span of time, tricking "Pokemon Go" into thinking that you're walking. If you're going to rely on this, it takes a while to really get going—it's likelier to work if you're inside a building (GPS is more accurate when you're outside), and you'll know it's working if you see your "Pokemon Go" avatar moving in the game (or the game thinks you're driving because you're moving too fast). This works better if you're trying to hatch an egg but you can't move around too much, but it's a slow way of incubating.
The next tip requires a signal emitter, which you will have to invest in. Just put your phone inside a box and turn on your signal emitter, which sends out fake signals. You can then change your phone's location within "Pokemon Go" using fake signals.
If you really want to tempt fate, you can play a cracked "Pokemon Go" app. We're not going to tell you where to find this apk; we're only going to say that it has a built-in location faker that you can use to "roam" the streets within the comfort of your own home. Be warned, though, as you're going to have to start over with a new account, and Niantic has been pretty tough cracking down on cheaters. They will find you.
Seriously, though, despite the danger in the world outside, "Pokemon Go" really is best enjoyed when you're walking around, trying to discover Pokemon you can catch. You don't have to make a new friend, but time outside is good for you.