On my computer I went to
http://invasion.tap4fun.com/, clicked the "Android" link to download the .apk, plugged my phone into my computer with the USB cable, copied the .apk file to the download folder on my phone. disconnected my phone from the computer, navigated to the download folder on the phone, tapped the .apk file and followed the prompts to complete installation. I did get a warning about installing an app in the fashion from the phone's OS but it allowed me to accept the risk and continue the installation. I did this on a Windows 7 x64 PC to my Verizon LG G2 android OS version 5.0.2