FYI: thoughts based on posting/studying CL ads, so application to SO may be limited.

Title
> ASP.net (c#) and Javascript Developer (Fast Growing Startup)

Straightforward title, like the inclusion of the type of company and type of work you will be doing (fast growing startup)

Job Description

> We're looking for a talented ASP.net (c#) and Javascript developer to work with us in our SW London office based in Twickenham.

Would probably include 'fulltime.' Would also suggest a short description of what the company does. You are kind of burying the lead by not saying "We develop a Windows program that lets anyone make HTML5 games." As a start up employee WHAT I'm working on is as/more important that what I'm doing in code.

Roles

> Develop our website

This is vague, are they working on a team? Make this more specific, are they in charge of design too? Do you have a designer?

> Help to develop a large separate Javascript web application

Also very vague, what would their role be here? How large is the team they would be working with?

> Perks
>
> Lots of opportunity for creative solutions to interesting problems
> We'll let you spec your own working computer! (within reason, we want you on the best stuff though!)
> Our website gets over 100k uniques per month and 1.2m page views, you'll often receive immediate feedback from our awesome community of game developers
> Pizza on fridays

These perks are rather vague/straightforward/drab. This is your chance to show your personality as a company (reframe in casual language you would actually use). For example: Instant feedback: with 1.2mm page views, if you push shitty code you'll know in seconds! (purely an example, do not advocate the word shitty)

> How we operate
>
> We're HTML5 evangelists!
> No dress code at all (as long as you wear something!)
> Highly flexible working hours (you might prefer 12-8 instead of 9-5, we can work with just about any hours you want)
> Open to the possibility of interesting side projects if you have any ideas

> You will be our first employee working at our fast growing startup! We're looking for quality applicants and are willing to pay a competitive salary to reflect this.

Again this is your chance to be quirky. "No dress code at all" could easily be "Wear what you want. We love nudists, just not at work."

You are hiding the salary talk at the end of the ad. This could easily be put as a bullet at the end of "how we operate" like: "Salary: we want the best and we'll pay you like we mean it." By hiding it down here, it is hard to find and I might miss it.

In general the thigns that people want to know:

- What I will be doing
- Who I will be doing it with
- Am I going to get money or equity?

Those should visually be easy to pull out. Roles does the first, you need to give them the other two.

> Skills & Requirements
>
> Must Have
>
> Highly proficient with ASP.net c# development
> Highly proficient with Javascript development
> Experience with Linq
> Experience with SQL Server
> Easy to get along with and love what you do!

Again a chance for personality. The more specific the better people with filter themselves out. Do you want someone with JS MVC framework experience, JS is a pretty big language with a ton of subtlety.

> Nice to Have
>
> C++ for Windows Development
> Enjoy making and playing games
> A sense of humour!
> About Scirra Ltd

Spice this up as well. Why is C++ a nice to have "we want you to help us write the games too!"

> Scirra was established in 2011 and we've been growing fast. We develop and sell Construct 2 in house, a Windows program that lets anyone make HTML5 games. To date, it's been downloaded over 200,000 times.
>
> Since day one of selling we've been profitable and revenues are continuing to grow. We're now looking for our first full time in-house employee!

Spice this up it sounds corporate.