To add "Half-Life" stickers to WhatsApp follow these steps:

• Download the Sticker Maker app from Google Play (Android) or from App store (iOS)
• Download the "Half-Life" sticker pack if the download doesn't start automatically.
• Click on downloaded file HL_Inside.wastickers and open it in Sticker Maker app.
• Click "Add to library" and then "Add to WhatsApp". Ok.
• Stickers added to WhatsApp! Thank you for using our site.