Cities: Skylines

The easiest way to do this is just to load up one of your saves that has bus lines unlocked. Pick an area of the map with a lot of roads. Build one new line, then add a stop, then hover over your original stop and complete the route. The line will automatically connect. Then, move to another street (or up the current street a bit) and repeat the process. You can do this all with your game paused.

Then, just quit out without saving.

I have a solution for this achievement that is extremely quick. You would need at least $325,000 to be able to do this.

First, save your current game, and then turn off auto-save if you have it on. Then you will want to construct a road away from your city that is fairly long. Build 5 bus stations along the road you just built. In the same tab where you bought the bus stations from, scroll all the way to the end, and click Bus Line. Face your line of bus stations from the side that is facing the road. You will now click one of the up arrows, click the road in-front of the station, and then click that same arrow again. Do this for every single arrow in the 5 stations, and this achievement will pop.

Now exit your game (so you don't have to actually spend the money), start again, and turn auto-save back on if you want it on.