Having completed 5 of 18 trophies (reaching tier 1 of the Spring Cleaning badge) granted the Steam user a Spring Cleaning background, 3 emotes, and a mystery box. Description of the box states:

This item might be useful in a future sale.
Earned for participating in the Spring Cleaning Event in 2018.

Any guesses? Personally, I predict the mystery box will relate to Valve's new card game, Artifact, and perhaps Steam users who have the box may obtain an Artifact card or a card pack. Why cards? Well, Valve has released items with price tags for other games the company has developed. CSGO has skins, Team Fortress 2 has the hats, Dota 2 has market items on the community market (I am vague on what Dota 2 has). I cannot deny Artifact might have marketable cards in the future. Even though the description mentions the box might be useful in a future sale does not indicate the item must relate to a sale; just that an event coinciding with a Steam sale is possible such as if Valve released extra information about Artifact during the summer sale for example.

Edit: To add to my prediction, Artifact on the Steam store has a 2018 release date.
2018 Spring Cleaning event page
Spring Cleaning market items
Mystery box listing

Edit: The Mystery Box contained cosmetics for your alien in the Summer Sale 2018 minigame called Saliens.
https://steamcommunity.com/saliengame/play/

5 years ago*

Comment has been collapsed.

Maybe additional xx% off for any purchase?

Maybe its like a lootbox that will give you any steam game. (doubt that, but it would be cool)

5 years ago
Permalink

Comment has been collapsed.

Maybe additional xx% off for any purchase?

This was my thought too. A "special" coupon that adds +some % on any existing sale.

5 years ago
Permalink

Comment has been collapsed.

This also crossed my mind, with an immediate follow-up along the lines of "...which might mean we'll get shittier discounts to compensate for the coupon"

5 years ago
Permalink

Comment has been collapsed.

A lootbox? Sure, but you gotta buy a key first to open it - introduced at the next big sale :P

5 years ago
Permalink

Comment has been collapsed.

It's a coupon.

5 years ago
Permalink

Comment has been collapsed.

yeah, nothing exciting or new

5 years ago
Permalink

Comment has been collapsed.

I'm gonna take a wild guess that it's a universal coupon that can be used only once or a limited amount of times. Like -15% on top of whatever the sale price already is or something like that. But honestly, it's probably related to another badge or (boring) stuff like that.

5 years ago
Permalink

Comment has been collapsed.

I would love an universal coupon. Especially if I can get a good price on something like Ni no Kuni II.

5 years ago
Permalink

Comment has been collapsed.

+1 to this! I am waiting in anticipation for a sale on that one xD

5 years ago
Permalink

Comment has been collapsed.

A pack of cards for Steam Summer Sale 2018

5 years ago
Permalink

Comment has been collapsed.

I don't think it will be a pack but definitely 1 card

5 years ago
Permalink

Comment has been collapsed.

Probably another box inside :3

5 years ago
Permalink

Comment has been collapsed.

Deleted

This comment was deleted 3 years ago.

5 years ago
Permalink

Comment has been collapsed.

It's a companion cube

5 years ago
Permalink

Comment has been collapsed.

or a cosmic cube

5 years ago
Permalink

Comment has been collapsed.

i'd rather prefer the Eye of Agamotto

5 years ago
Permalink

Comment has been collapsed.

It'll give a collectible figure, when you collect certain amount of figures you can trade them for discount coupons and even games.

5 years ago
Permalink

Comment has been collapsed.

What's in the box?:)

A pair of new Socks. :)

5 years ago
Permalink

Comment has been collapsed.

People are listing it, I can't list it, sad on me.

For me, some old game or 3 cards for the next summer event.

5 years ago
Permalink

Comment has been collapsed.

The mystery box was marketable, but Valve disabled it. The feature was not intended.

Here is a response from a Valve employee: https://www.reddit.com/r/Steam/comments/8lue1l/got_this_after_completing_all_the_projects_wonder/dzii3vl/

5 years ago*
Permalink

Comment has been collapsed.

Soon as I receive the box I check if it can be solded on market but no, now I saw this and I was like; wtf - but good to know.

Edit: Oh thanks for the Reddit

5 years ago
Permalink

Comment has been collapsed.

Deleted

This comment was deleted 11 months ago.

5 years ago
Permalink

Comment has been collapsed.

a cat

5 years ago
Permalink

Comment has been collapsed.

Maybe a Gordon Freeman lookalike cat.

5 years ago
Permalink

Comment has been collapsed.

It's probably chocolate!

I'd be amused if Steam would determine the content of the box by how serious the account owner was involved in their spring cleaning.
Example:
If you just started and closed games, you'd get some rather useless coupon.
If you actually invested time and got plenty of achievements, you'd get a 10€ voucher, only usable during the summer sale.

They'd avoid that people cheat (knowingly), as all qualifying events would be a part of the past, once when they share the rewards.

5 years ago
Permalink

Comment has been collapsed.

That would be a pretty neat idea, and a kick in the face for a handful of us (including me).

5 years ago
Permalink

Comment has been collapsed.

It would include me too.
I imagine though that they wouldn't want to disappoint us too much, in such a scenario. ;)

5 years ago
Permalink

Comment has been collapsed.

Then they would be pretty crazy, expecting people to play like 16 full games in 4 days.
Even if people did like me and I just picked the really short games to try, complete, then idle for cards. 0_o

5 years ago
Permalink

Comment has been collapsed.

I didn't suggest that people would have had to fully play several games.
They could either use fixed requirements as x hours played in total etc. or they could reward the top 10% of the most active players with the best prize category, the next y% with the second best rewards category and so on. Nothing crazy about it, just something new.

5 years ago
Permalink

Comment has been collapsed.

its mulit coupon not 1 >.> its be 90% 50% 33% 10%

5 years ago
Permalink

Comment has been collapsed.

Half Life 3.

5 years ago
Permalink

Comment has been collapsed.

a cake... who's also a lie

Im with the coupon option too :S

5 years ago
Permalink

Comment has been collapsed.

living cat

5 years ago
Permalink

Comment has been collapsed.

Something disappointing.

5 years ago
Permalink

Comment has been collapsed.

Deleted

This comment was deleted 2 years ago.

5 years ago
Permalink

Comment has been collapsed.

+1

5 years ago
Permalink

Comment has been collapsed.

The head of Tracy Mills!! (from the movie Seven) O.O

In all seriousness, probably a coupon. Knowing Valve, it will probably be for Artifact.;)

5 years ago
Permalink

Comment has been collapsed.

A teaser trailer for HL3, coming summer 2028 (no relation with the Half-Life series, the letters stand for something else).

5 years ago
Permalink

Comment has been collapsed.

a 99% off coupon for a $80 special edition game, so people can come to the forums and complain how they have no money to buy it. T_T

5 years ago
Permalink

Comment has been collapsed.

Deleted

This comment was deleted 5 years ago.

5 years ago*
Permalink

Comment has been collapsed.

I beat you by an hour.;)

Although I am surprised that no mentioned that scene right away! LOL!

5 years ago
Permalink

Comment has been collapsed.

Deleted

This comment was deleted 5 years ago.

5 years ago
Permalink

Comment has been collapsed.

That could very well be! I am turning 45 on June 22nd, after all!;)

5 years ago
Permalink

Comment has been collapsed.

Deleted

This comment was deleted 5 years ago.

5 years ago
Permalink

Comment has been collapsed.

But wouldn't that have made you 28?;) ;)

5 years ago
Permalink

Comment has been collapsed.

Dissapointment :3

5 years ago
Permalink

Comment has been collapsed.

An item to be used in their pixel point and click.

5 years ago
Permalink

Comment has been collapsed.

A hat obviously

5 years ago
Permalink

Comment has been collapsed.

Pain.

5 years ago
Permalink

Comment has been collapsed.

Sign in through Steam to add a comment.