That was just a guess...
VPOKE is used to draw graphics to screen. VPEEK is used to read graphics from screen. These commands can't really be used for anything more interesting.
POKE is used to either write program to memory OR change some variables in memory, that can't be changed (or are not practical to change) other ways OR then POKE is just used to store bytes to memory in purpose to speed up arrays, when BASIC own arrays are too slow.
PEEK is typically used to read arrays or variables from memory as usually reading ML program from memory is not very interesting thing to do unless you are writing disassembler in BASIC.
In this case it might be that then the program either uses BIOS routines or the code is included in the BASIC program. Purpose to put bytes to memory is to write a ML code, that can be executed with DEFUSR & USR commands.
Here is an example of simple BASIC program:
10 beep:beep:beep
Here is an example of same program written using BEEP command from BIOS jump table:
10 DEFUSR=&HC0
20 A=USR(0)+USR(0)+USR(0)
Here is an example of home made ML program located at #C000, that executes BIOS BEEP command 3 times.
10 for i=0 to 8: read a: poke &HC000+i,a: next
20 defusr=&HC000: a=usr(0)
30 data 205,192,0,205,192,0,195,192,0
Hope this clears the idea a bit.
For more information:
Here is some more information about BIOS routines:
http://fms.komkon.org/MSX/Docs/BIOS.txt
Here is a list of ML op-codes, that you can POKE to memory to make your own programs:
http://www.z80.info/z80oplist.txt
I must anyway tell you, that most propably even those, who wrote your mentioned games, first made their routines in assembler, compiled them, tested them and then in last phase converted them to memory dump, that is written to memory by the BASIC program, you are able to see. This is propably done to make it possible to print the program to magazine.
From here you can also follow links to learn more about inner mind of Z80 CPU, that is the core of MSX:
http://www.z80.info/
Here is pretty good summary of MSX in general although quite some info is roughly generalized and violates MSX standard. This anyway should get you started:
http://www.work.de/nocash/portar.htm
To learn about usage of VPOKE and VPEEK, click first "Video Display Processor" and then "Video Modes"
To learn some basics about variables stored in RAM, look here:
http://fms.komkon.org/MSX/Docs/SysArea.txt
To learn, how to do things right and according to MSX standard I recommend you to read MSX2 technical handbook, that can be found from here:
http://www.konamiman.com/msx/msx-e.html