XX Mission is a standard shoot 'em up with no stand-out features. It might have been more interesting with an additional X.
Hidden Credits#
There's a set of credits (and a build date) hidden in the game that can be accessed by entering and activating the following code in MAME's xxmissio.xml cheat file.
<cheat desc="Game Credits">
<script state="on">
<action>maincpu.pb@E146=01</action>
</script>
<script state="off">
<action>maincpu.pb@E146=00</action>
</script>
</cheat>
Not content with having just one set of hidden credits, another is stored in the sub-CPU starting at 0x00FC:
Music,effect and Produce By T.fujisawa
Software By S.Satoh
Desing By A.tsunoda and T.fujisawa
1986 UPL Limited !
Since you can never credit Tsutomu Fujisawa enough, there's an additional credit in the object graphics bank.
(XX Source: Original TCRF research)