> ## Knowledge Base Index
> Fetch the complete knowledge base index at: https://help.drimify.com/sitemap.xml
> Use this file to discover available pages before exploring further.
> Pure-Markdown content can be obtained by appending a '.md' suffix to the content URLs listed in the sitemap (without the trailing slash).

# Can I make sure each person wins only once?

**Short answer: you can make it very hard to win twice, but no game open to the public can guarantee it 100%.** Every limit relies on one piece of information (an email, a phone number, an ID). If someone uses a second, real email address, the system sees a new person.

How strong your protection can be depends on who your game is for.

# Players who log in: the strongest option

If your players already log in to your website, app or customer area (for example with SSO), send their account ID to the game with the [Session Unique ID](https://help.drimify.com/en/article/session-unique-id-1u3ctjk/). Then base the [participation limit](https://help.drimify.com/en/article/limit-by-unique-session-id-coil0a/) and the prize winning limit on this ID.

The ID comes from your own login, so one account means one player. A second email address changes nothing.

# Physical events and shops: unique codes

Hand out one unique code per visitor (on a flyer, a receipt or a ticket at your stand). Upload the list of codes in [Access Control](https://help.drimify.com/en/article/access-control-1k0lnzk/) with identification based on **Unique identifier**, then limit participation to one play per code.

Only people with a valid code can play, and each code works once. You decide how many codes you give out, and to whom.

# Games open to the public: combine three settings

1. **Limit wins:** in the **Game Configuration** step, tick **Enable the prize winning limit** and set 1 prize per person, based on email or phone number. See [Prize Management](https://help.drimify.com/en/article/prize-management-6rng5p/).
2. **Limit plays:** in the **Settings** step, limit participation by email or phone number. See [Limits and restrictions of participation](https://help.drimify.com/en/article/limits-and-restrictions-of-participation-qkr7n5/). Drimify already ignores common email tricks (capital letters, "+" tags, dots in Gmail addresses).
3. **Make each prize single-use:** give vouchers as [unique promo codes](https://help.drimify.com/en/article/distributing-promo-codes-through-your-app-12ovcau/), so each code can be used only once.

|| The prize winning limit and the participation limit are two different settings. Use both: one limits prizes, the other limits plays.

# Your terms and conditions

Settings stop most repeat entries, and your rules cover the rest. We recommend you state:

* One prize per person (or per household)
* The organiser may ask for ID when the prize is collected or the voucher is used
* The organiser may cancel any win that breaks the rules

# Check winners before sending prizes

Open your [data export](https://help.drimify.com/en/article/how-does-the-data-export-work-1aap30i/) and look for winners with the same first name, last name and postcode. Two emails with the same name and address are easy to spot.

# Make a second win less costly

For vouchers, add a minimum purchase: for example, 30 off a purchase of 50 or more. A second win then still brings a sale, not only a cost.