Alternatively, are you playing the version of rugby called sevens? Are you practicing late in the season and giving your sore soles a rest? Are you morally opposed to hurting someone when you stamp on them? Okay, I'm kidding with the last one. Seriously, if you don't like violence, there's always tennis.
At any rate, if the answer to any of these questions is "yes," molded cleats are for you. These are basically soccer shoes, and no one will think less of you for wearing them... much.
If you feel strange wearing soccer boots to play rugby, companies like Canterbury of New Zealand (see photo) make molded cleats for use on turf, hard ground, or to play sevens where speed is more important than any other concern (including inflicting or avoiding pain). Molded rugby cleats are more or less the same as soccer cleats, but are made with the understanding that they will used to play a more violent sport, and so are more durable than soccer cleats.
But unlike with the boots described above, where you really are better off getting boots specifically made for rugby, the distinction is not as important here. The assumption is that the ground is going to be unforgiving in a way that actually makes it counterproductive to wear screw-in cleats (trust me, the soles of your feet will be shredded and your knees will ache more than they normally would), and this overrides any other advantages the screw-in cleats will provide you.
In addition, playing on hard ground or artificial grass changes the nature of the sport. Tactical kicking becomes more effective because the ball bounces higher when it hits the ground, the game opens up as a result, and there's less call for the type of close play that necessitates using one's feet for raking or stamping. This is also true in sevens, which is more about running and passing and less about mauling and tackling. All things considered, in these conditions, your best bet is a light shoe with small cleats - that is, soccer boots with molded cleats.