If you're not too sexy for power-ups, continue reading...
As you've seen, SteroidS has many humorous elements, references and easter eggs, and power-up designs show that. Right now there are two different power ups, plus another one that is included on the next update (due in a week or so).
For the the +1UP power-up, I wanted something very Mario-ish, and in general, power-ups are box-based things like in Mario. So the design turned out to be this yellow box with orange edges, very Mario-like, with the face of the scientist on it.
This power up gives the player an extra life, obviously, but it's limited so that you can have a maximum number of 3 lives. The thing is power-ups appear at random so I wanted to prevent people from collecting a countless number of lives, thus making the game harder.
The "Nuke all thugs" looks like a companion cube, but it has the crossed-out heart. Everybody loves the companion cube, and adding the crossed-out heart made sense since this power-up is somewhat of a "kill all enemies bomb" found in these kinds of games.
When designing the "Nuke all thugs" power-up, I found myself wondering what kind of "look" it should have. I didn't want a bomb-looking thing, or something with a skull and 2 bones, so took a look at what other games had, and how it could be twisted a little to fit our game, and the choice ended up being the companion cube (after all Portal is also a goofy kind of game).
For a more technical aspect of this power-up, it's actually pretty simple. All I had to do is code a projectile with a massive damage value, and a huge damage radius. The projectile is invisible, and it's fired via Kismet every time the player picks the power-up. Thanks to the high damage and radius, it kills everything on the level. Now the thing is the projectile would obviously kill the player too, so I had to use a custom damage type for it, and tell the player to ignore that damage type, so everything but the player gets affected by it (in other games that's how you could create resistances for certain elements, for example a character that's immune to fire and such).
The last power-up I'm covering is included on the next update (version 2.0) and it's called the BSG (I'm glad you picked up that reference too). The BSG, Big Steroids Gun, allows the player to shoot faster, and more powerful bullets for a limited period of time. These bullets kill everything with one hit, so it gives you some time to recover from the enemies' steroids boost.
The design for that power-up (no image yet) is a glowing pulsating box. The idea was to give the impression of something "containing a big amount of power," besides we needed it to be easily recognizable.
Since we implemented a very open design on SteroidS, we can add more features, including power-ups on future releases. This means we will be adding more on upcoming updates, but we will also add more enemies and gameplay modes.
Remember there's a demo version available here on our IndieDB page. If you want to own the full game, get it on Indievania now.