DrumAllDay
I think the route you decide to take will depend on the complexity of your application. Like you said, you could go with a single application that has a single markup file and hides the sections you don't need and moves the focus to the part of the markup you do need.
Or, the initial markup page could be your selection page, and then load a new markup page for either of the quiz games.
Or, should your applications get even more complex, you could make your selection application a playlist application. And, then each of the quiz applications could be its own title application in its own title. then your playlist application would switch between titles in order to load your other applications.
in this case, your playlist would look something like:
<TitleSet defaultLanguage="en" timeBase="60fps">
<Title id="movie_only" titleNumber="1" tickBaseDivisor="1" titleDuration="01:00:00:00" >
<PrimaryAudioVideoClip src="file:///dvddisc/HVDVD_TS/EVOB.MAP" titleTimeBegin="00:00:00:00" titleTimeEnd="01:00:00:00" dataSource="Disc">
<Video track="1" mediaAttr="1"/>
<Audio track="1" streamNumber="1" mediaAttr="1"/>
</PrimaryAudioVideoClip>
</Title>
<Title id="quiz" titleNumber="2" tickBaseDivisor="1" titleDuration="01:00:00:00" >
<PrimaryAudioVideoClip src="file:///dvddisc/HVDVD_TS/EVOB.MAP" titleTimeBegin="00:00:00:00" titleTimeEnd="01:00:00:00" dataSource="Disc">
<Video track="1" mediaAttr="1"/>
<Audio track="1" streamNumber="1" mediaAttr="1"/>
</PrimaryAudioVideoClip>
<ApplicationSegment titleTimeBegin="00:00:00:00" titleTimeEnd="01:00:00:00" src="file:///dvddisc/ADV_OBJ/quiz.aca/manifest.xmf" autorun="true" zOrder="0">
<ApplicationResource size="999999" src="file:///dvddisc/ADV_OBJ/quiz.aca" multiplexed="1" priority="1"/>
</ApplicationSegment>
</Title>
<PlaylistApplication language="en" src="file:///dvddisc/ADV_OBJ/playlist_app.aca/manifest.xmf">
<PlaylistApplicationResource size="999999" src="file:///dvddisc/ADV_OBJ/playlist_app.aca" multiplexed="1"/>
</PlaylistApplication>
</TitleSet>