Valve's Team Fortress 2 team are running a competition whereby the entire Tomb Raider franchise is fair game for TF2 Workshop content creation. Their official blog post on the matter goes straight for "the heavy in short shorts" at their first example of the contest's potential*. But why on earth would you want to help Valve and Square promote a game for free? Let's take a look at the rules.
As per the official TF2 post:
"Rather than working with the developers to have them produce some promotional content for the upcoming Lara Croft and the Temple of Osiris that we hope you'll like, we're involving all of you guys directly — you who submit content to the Workshop and who vote on it."
The winning entries will then be given away as pre-order incentives for Lara Croft And The Temple of Osiris on Steam.
These types of competition can be ethically questionable as the benefit tends to skew heavily in favour of the company rather than the entrant. They don't have to pay a marketing team, an agency or a designer, they raise awareness of their product through the entrant's quest for votes and they might well get some brilliant (and profitable) content out of it. The benefits for the creator tend towards a nebulous promise of exposure and perhaps some typical prize fare – a framed copy of your design or an edition of the product the competition was promoting – that kind of thing.
I've had a poke about in the rules for this one and the rewards are as follows:
You get the majority of Square's back catalogue via Steam as well as a copy of Lara Croft And The Temple Of Osiris. The items may also be given away or sold to TF2 players. If sales are involved the entrant gets the same 25% revenue share arrangement as they would if creating regular TF2 workshop content.
The part about revenue share is positive, and the list of games you'll get from Square's back catalogue is substantial. The implicit idea of exposure to a wide audience is a more complex one when it comes to Steam.
The platform does have the power to reach a lot of people and interest in the Tomb Raider franchise is high. 2013's Tomb Raider apparently had 1 million players within the first couple of days (although we don't know how many were Steam pre-orders). It's also impossible to know whether the experience and potential attention you could get as a result will be useful or lead to new opportunities. It might – Gabe Newell noted that some Steam Workshop creators make over $500,000 per year - but it might very well not.
The point I'm making is that, no matter the framing, these types of contest invite an active and creative community to do design work free-of-charge for a company who will then use it as an incentive to get people to buy their product. Whether the potential benefits outlined above make entering worthwhile for you personally is the question, but you should consider that when this work is given as a commission to a designer it is paid for.
*They add "Please don't do this" but it's probably some reverse psychology on their part.