Old question, but I'm shocked about some of the answers so I had to respond. I volunteer quite regularly with children your daughters age. I'm also a geek, and gamer when i have free time.
The first thing I will say is that there is nothing inherently wrong with games! There is a real sigma in some people's answers, but It reminds me of the trope new media are evil. There is a dislike of gaming to an extent just because it's new. By themselves games are not bad.
What is bad is leaving a child with any form of entertainment that keeps you away from them for extended lengths of time. This can be playing simple video-games, or watching tv. It also could be the child coloring or playing with blocks alone. The biggest problem is not the activity, it is when parents stop spending time with children and leave anything as a substitute for parental involvement.
In your case your involved with your child during these brief game sessions, and that's good! Any form of involvement will be good for her, it doesn't matter if it's play with blocks or video games. The bond is still being built and that is a good thing!
The other criticism you hear is that games are not stimulating enough, and this I highly disagree with. Appropriate games, like the very one you mentioned, stress the brain significantly. It requires problem solving and reasoning skills, learning and creativity. This is going to stimulate her brain, in fact 15 minutes every day or two of playing a game like this is much better for her then more time coloring or playing with blocks, not because games are better, but because it's good for a child to get many different forms of stimulus and practice. If she already colors often then more coloring isn't likely to teach her something new, but a new game for a little while may teach her some reasoning skills to solve the puzzles, or allow a new form of creativity in more sandbox/creative games. It's an alternate mode of practicing her mind.
Furthermore, I like that a girl is playing these sort of games with you. It's well known fact that girls are far less present in STEM fields, likely at least partially due to society teaching girls that they shouldn't focus on these fields. While I don't think 15 minutes of playing games is going to have a significant affect one way or another here, I would stress that you are encouraging her to use a computer to it's full extent and to learn what she can do it. This can make her more comfortable with computer use in general at an early age, which could have a small increase in the odds of her sticking with computers and technology rather then society 'teaching' her that they are not somehow a 'girls' task. I'm a judge for middle school robotics competition call FLL, I'm judging all this weekend actually, and there are far fewer girls then boys participating, but I have noticed the girls that do are more likely to call themselves gamers, suggesting there could be a correlation.
So I see nothing wrong with your current involvement and occasional playing with her, if anything I think it's positive. The important thing is that this involvement includes your interaction with her, and that interaction is the real strong point. I honestly wouldn't mind seeing more of it, if she were interested in doing so of course.
In fact to get more out of it I would suggest you try alternating the games around every now and then, show her many different sorts of games, especially of the puzzle and builder/sim/creativity variety. Help her to learn that there are challenges here that she can learn to tackle with your help. Perhaps, when she is ready, which she may not quite be up to yet, get her started with some of the early programming games for kids. I'd also keep encouraging her to learn to use the mouse, though not to pressure her if she is really resistant, as it is a good tool to learn. Basically while playing games also encourage her to look at the computer as a tool that she can learn to use fully, that it can do many things but if she invests some time into learning she can make it do the stuff she wants from it.
Of course I stress that games used to supervise kids is bad. If she got to the situation where she was spending a large amount of time with games alone then encourage her to do other things with you, this is the same as if she was coloring or watching tv for too long alone. The advantage to your playing with her now are that it is still rather novel and thus a good learning experience, and that you are interacting and bonding with her while doing it.
Beyond all that I would add, caring for children is all that really matters. Don't let people make you think you have to do things in a certain way, so long as your with your child and she is happy (and not obviously spoiled I suppose) then your doing a good job parenting, whatever activity your doing with her.