Hi there!

I am in a bit of a legal/moral dilemma: I recently released a beta version of my first android game and the responses are really positive (both comments and ratings, number of downloads: meh, but that's another story). While that makes me really happy, I "kinda" based my game a bit too much on an existing freeware game: the incredible Star Guard. I didn't intent to blatantly rip off Star Guard and profit from another indie developer's efforts but it seems like I am. How it happened:
About 5 months ago, I decided to look into Android game programming as I was intrigued by the new possibilities the platform offered (I also tried out iPhone development but without an actual iPhone, it wasn't much fun). I scanned the market to see what I would like to play on a smartphone but wasn't present yet. I tried the available jump'n'run games and found none of them particularly enjoyable. At about the same time, I discovered Star Guard and found it absolutely fantastic. So I decided: take the basic game-play from Star Guard and try to port it to the android platform. This started as a learning project to get me familiarized with the SDK, the development, the different phone models and so on. I had so much fun doing it that about 3 months later, I had a first playable and fun version.

I was like "Cool, but what do I do with it?". In the course of the next weeks, I tried to contact the author of Star Guard. I wrote several E-mails and I asked if I was allowed to release it to the public. Unfortunately, he didn't respond at all.

Still having fun working on my "port", I continued and the urge to release it on the android market rose. Finally, after googling things like "illegal freeware game clone", I decided what the hell and released it as a freeware game. In my mind, a couple of things can happen:

• The original author doesn't care

• He does care but is fine with it but decided not to respond for whatever reason

• He deliberately didn't respond to sue me after I release it... (I doubt that)

• He didn't read any of my mails (doesn't check his account anymore, spam-filter, ...

• 

Maybe somebody with a little legal background can help me here: what's the worst I have to expect? Cease and desist? Or worse? It really wasn't my plan to rip off someone...

I made no money releasing the game. I would like to if it's possible but before this issue isn't resolved, I can't.

Anyway, if you like, here is the link to my game (or search for "star warrior" in the market). You will need an Android phone of course.

Thanks for your input!

I tried installing through your link, as searching for "Star warrior" on the Market returned no results, but I was told that the item was not compatible with my device.

Agreed about the legal issues mentioned so far.

As far as the game goes, I had a lot of trouble shooting while in mid air; the presses just would not register. Also my device uses soft buttons so the right 20 pixels or so (approx.) are unusable. The 'J' label is slightly cut off, though both S/J actions still work, seemingly offset to the left a bit. I don't know how you're supposed to detect the usable screen space; apparently many games have a problem with this.

That's not technically true. If the copyrighted material was wrongly distributed then redistributing replacement material doesn't necessarily undo the distribution of the copyrighted material. I'm sure it's still possible for the original copyright owner to make a case against you. Besides, you can't actually force data onto somebody's device (nor off of it). The carrier/distributor might try to force it, but that can always be hacked, if not just denied service. Especially if the updated content isn't as high quality as the originally distributed content (if the OP was capable of that then he probably would have had it done in the first place). Users are going to complain and warn others not to update. If the carrier/platform/device/OS insists upon updates then it will encourage hackers to hack the system. For all intents and purposes once the damage is done it's done. You just have to hope that those with rights in the matter don't mind.

Game designs cannot be patented either. (Note that while there are a few game design related patents out there, I don't think they're all valid and they're more specific than this. You certainly can't patent an entire game.)

Now, looking at assets... those are very simple assets. It's literally tiny 1-bit dudes in various colors. Which is why I think it's a bloody shame, and definitely illegal and even assholish, that you had to rip specific sprites like that. Just make your own. It's not hard to be consistent with that style if you really want it, but what you're doing right now is not kosher.

Thanks for your input!

Looks like my concerns have come true. So I will have to roll an update with different graphics... Not easy for me as a non-artist, but I'll try.
But how different is different? As X-G pointed out, they are "simple" 1-bit graphics. If I stick to this style, I might end up with something very similar as the possibilities are not vast. I did draw the current graphics, I just took the original ones as a reference (I know that doesn't make it more legal). Do I have to go a different style as well?

As for having problems playing the game:

Your device doesn't meet the necessary requirements. The market only shows items available to your phone, sorry.

That is odd! I've never experienced anything like this. Could you please tell me your phone model and your android version? Does your phone support multi-touch? As for shooting while jumping, that a limitation of the touchscreen. If you try to press both 'J' and 'S' at the same time with the thumb, it will recognize it as only one press. I can't change that.

edit:
Not trying to defend myself by pointing at others, but there are numerous (bad) Super Mario games on the market that use the original graphics. It seems like android doesn't do anything about it and nobody seems to care. Are these graphics public domain already? I am talking about games like this. Shouldn't the authors of those game be in even more trouble than I am?

Yeah, my phone is a very entry-level Android device.

Even my phone is not compatible.

I don't even have pinch zoom (and I do have 2.1)

I don't know about video games, but I do know that there are chess-variant games that are or were under a (US) patent, for instance Falcon Chess and formerly Gothic Chess. Quite how you can patent something as trivial as the rules of a chess-like game with a couple of (in the case of Gothic, well known) fairy pieces is beyond me, but apparently you can.
Don't know if those patents would hold up if challenged though.

There are a lot of patents that have snuck through the USPTO, but that doesn't mean those things are actually patentable. In short, those are errors and should never have been allowed to be patented. In Europe, the EPC specifically outlaws it, in fact:

Emphasis mine. In the United States, it's less clearcut, but the same sentiment is expressed:

Generally, rules for games have never been considered to have "useful" application. In short, the patents you referred to are most certainly invalid patents and would crumble if you poke them.

Can we see screenshots of the new graphics?

Well I was reading this: http://forums.tigsource.com/index.php?topic=17029.0

and remembered your post... tan tan tan...